How to Cook Costco Lasagna Perfectly

Kirkland Signature Italian Sausage and Beef Lasagna is a frozen meal sold at Costco warehouses. Each twin pack contains two 3-pound trays with layers of pasta, meat sauce, ricotta, and mozzarella cheese.

This frozen lasagna works well for family dinners, potlucks, or meal prep nights when you need something filling without the effort. One tray feeds 4 to 6 people comfortably.

This guide covers 4 cooking methods. Time ranges from 25 minutes (microwave) to 70 minutes (conventional oven). Equipment needed includes a baking sheet, food thermometer, and aluminum foil.

Product Details

Product: Kirkland Signature Italian Sausage and Beef Lasagna

Type: Frozen, ready to cook (no thawing needed)

Package Size: 6 lbs total (two 3 lb trays)

Servings: 6 per tray, 12 total

Price: $17 to $20 at Costco (Updated January 2025)

Storage: Keep frozen until ready to cook

Calories per Serving: 410

Main Ingredients: Vine-ripened tomatoes, cooked pasta, Italian sausage, USDA Choice ground beef, whole milk ricotta cheese, whole milk mozzarella cheese, parmesan cheese, romano cheese, spinach, red wine, garlic, caramelized onions

Item Number: 1321637

Cooking Methods Comparison

Recommended Method: Conventional oven for the best balance of crispy mozzarella topping and fully heated center.

Method 1: Conventional Oven (Recommended)

The oven method takes about 60 to 70 minutes total. You get a golden brown cheese layer on top with bubbling edges. This works best when cooking a full 3-pound tray for 4 to 6 people.

Step 1: How Do You Prepare the Lasagna?

Keep the lasagna frozen. Do not thaw before cooking.

Instructions:

1. Remove the outer plastic wrap and cardboard sleeve from the twin pack
2. Separate the two trays
3. Leave the clear plastic film on top of the tray
4. Cut a 2-inch slit in the center of the film to vent steam

Equipment: Baking sheet, sharp knife or scissors

Step 2: What Temperature and Time Do You Use?

Preheat to 375 degrees F. Total baking time runs between 60 and 70 minutes depending on your oven.

Instructions:

1. Set oven to 375 degrees F (190 degrees C)
2. Place lasagna tray on a baking sheet
3. Position on the center oven rack
4. Bake covered for 50 to 55 minutes

Temperature: 375 degrees F

Time: 50-55 minutes covered, then 10-15 minutes uncovered

Step 3: When Do You Remove the Film Cover?

Remove the plastic film after the first 50 to 55 minutes. The cheese needs direct heat to brown properly.

Instructions:

1. At the 50-minute mark, carefully peel back the plastic film
2. Return to oven uncovered
3. Continue baking 10 to 15 minutes until cheese turns golden brown

Checkpoint: At 50-minute mark, internal temp should be around 145 degrees F

Step 4: How Do You Know When It’s Done?

Check for bubbling around the edges. The center must reach 165 degrees F for food safety.

Instructions:

1. Insert a food thermometer into the center of the lasagna
2. Confirm internal temperature reaches 165 degrees F
3. Look for bubbling marinara sauce around the edges
4. Remove from oven and let rest 5 to 10 minutes before cutting

Target Temperature: 165 degrees F minimum

Visual Indicator: Golden brown mozzarella on top, sauce bubbling at edges, steam rising when cut

Method 2: Convection Oven

Convection ovens circulate hot air, so you can lower the temperature and still get even cooking. Total time drops to about 45 to 60 minutes.

Step 1: How Do You Prepare the Lasagna?

Same preparation as conventional oven. Keep it frozen.

Instructions:

1. Remove outer packaging from frozen lasagna tray
2. Keep plastic film in place
3. Cut a 2-inch vent slit in the film
4. Place on baking sheet

Equipment: Baking sheet, knife

Step 2: What Temperature and Time Do You Use?

Lower temperature by 25 degrees compared to conventional oven. The fan does the rest.

Instructions:

1. Preheat convection oven to 350 degrees F
2. Place lasagna on center rack
3. Bake covered for 40 to 45 minutes

Temperature: 350 degrees F

Time: 40-45 minutes covered, plus 5-15 minutes uncovered

Step 3: When Do You Remove the Film Cover?

Remove the film after 40 to 45 minutes to allow the cheese layer to brown.

Instructions:

1. Check at 40-minute mark
2. Remove plastic film carefully
3. Continue baking 5 to 15 minutes until golden

Checkpoint: At 40-minute mark

Step 4: How Do You Know When It’s Done?

Same indicators as conventional oven. Temperature and visual cues matter most.

Instructions:

1. Check internal temperature at center
2. Confirm 165 degrees F
3. Let stand 5 to 10 minutes

Target Temperature: 165 degrees F

Visual Indicator: Golden cheese, bubbling edges

Method 3: Microwave

The microwave method takes 25 to 30 minutes. You sacrifice the crispy top for speed. Works fine when time matters more than texture.

Step 1: How Do You Prepare the Lasagna?

Frozen, straight from the freezer. Same as other methods.

Instructions:

1. Remove outer packaging
2. Keep plastic film on tray
3. Cut a 2-inch slit in film for venting
4. Place tray in center of microwave

Equipment: Microwave (1000+ watts works best)

Step 2: What Power Level and Time Do You Use?

Two-stage cooking. High power first, then 50% power to heat through without rubbery edges.

Instructions:

1. Microwave on HIGH (100% power) for 10 minutes
2. Carefully remove plastic film
3. Lower power to 50%
4. Continue cooking 14 to 17 minutes

Power Level: HIGH for first stage, 50% for second stage

Time: 10 minutes + 14-17 minutes = 24-27 minutes total

Step 3: When Do You Check the Lasagna?

Check after the second stage. Microwaves vary, so your timing might need adjustment.

Instructions:

1. After 50% power stage, check internal temperature
2. If below 165 degrees F, continue in 2-minute increments

Checkpoint: After 24 minutes total

Step 4: How Do You Know When It’s Done?

No crispy top with microwave. Focus on internal temperature only.

Instructions:

1. Insert thermometer into center
2. Confirm 165 degrees F
3. Let stand in microwave 5 minutes
4. Let stand outside microwave 5 more minutes

Target Temperature: 165 degrees F

Visual Indicator: Cheese fully melted, sauce bubbling, steam rising

Method 4: Air Fryer

Air fryer works if your basket fits the tray (or a portion). Total time runs 35 to 40 minutes with a nice crispy cheese top.

Step 1: How Do You Prepare the Lasagna?

Check if the full tray fits your air fryer basket. Most basket-style air fryers require portioning.

Instructions:

1. Remove packaging and plastic film
2. If tray fits, place directly in basket
3. If too large, transfer portion to oven-safe dish that fits

Equipment: Air fryer (oven-style works better than basket for full tray)

Step 2: What Temperature and Time Do You Use?

Start low to defrost, then increase temperature for browning.

Instructions:

1. Preheat air fryer to 250 degrees F for 3 minutes
2. Place lasagna in basket
3. Cook at 250 degrees F for 10 minutes to defrost
4. Increase to 350 degrees F
5. Cook 25 to 30 minutes until done

Temperature: 250 degrees F (defrost), then 350 degrees F (cook)

Time: 10 minutes + 25-30 minutes = 35-40 minutes total

Step 3: When Do You Check the Lasagna?

Check at the 30-minute mark. Air fryers brown quickly once heated.

Instructions:

1. At 30 minutes total, check cheese color
2. If not golden, continue 5 more minutes

Checkpoint: At 30-minute mark

Step 4: How Do You Know When It’s Done?

Same temperature target. Air fryer gives you crispy top faster than conventional oven.

Instructions:

1. Check internal temperature
2. Confirm 165 degrees F in center
3. Let rest 5 minutes before serving

Target Temperature: 165 degrees F

Visual Indicator: Golden brown top, crispy edges, bubbling sauce

Safety and Quality Indicators

Food Safety

• Internal Temperature: 165 degrees F minimum
• Steam Check: Product should steam when cut open
• Thawing: Never thaw before cooking. Cook directly from frozen.

Quality Indicators (Done Properly)

• Color: Mozzarella topping should be golden brown with some darker spots
• Texture: Pasta layers firm but not crunchy, cheese stretchy when pulled
• Temperature: Hot throughout, no cold spots in center
• Appearance: Sauce bubbling around edges, steam visible when cut

Signs of Overcooking

• Cheese becomes dark brown or blackened
• Edges are dried out and hard
• Sauce has evaporated, leaving dry pasta layers
• Bottom of tray shows burned residue

Serving Suggestions

Portion Size: 1 cup (about 226g) per serving, 6 servings per tray

Serving Ideas

• Slice into 6 pieces by cutting once lengthwise and twice horizontally
• Add fresh basil on top after removing from oven
• Sprinkle extra parmesan cheese before serving

Pairing Recommendations

• Caesar salad on the side
• Costco garlic bread pairs well with this Italian dish
• Steamed broccoli or Costco frozen vegetables
• Red wine (Chianti or Sangiovese)

Storage and Reheating

Leftover Storage

• Refrigerate within 2 hours of cooking
• Store in airtight container or wrap tray with plastic wrap and foil
• Consume within 3 to 4 days
• Can freeze leftovers for up to 3 months

Reheating Instructions

• Microwave: 1 minute on HIGH, then 30-second intervals until hot
• Oven: 350 degrees F for 20 to 25 minutes, covered with foil
• Target Temperature: 165 degrees F

Tip: Add a splash of marinara sauce before reheating to prevent drying out.

Troubleshooting Common Issues

Issue: Center is still cold

Cause: Oven not preheated fully, or cooking time too short

Solution: Always preheat oven completely. Use a food thermometer to check center temp. Add 10-15 minutes if needed.

Issue: Cheese burned before center cooked

Cause: Film removed too early or oven temperature too high

Solution: Keep film cover on for first 50 minutes. If cheese browns too fast, tent with foil.

Issue: Lasagna falls apart when serving

Cause: Not enough resting time

Solution: Let stand 10 minutes minimum after removing from oven. The layers set as it cools slightly.

Issue: Sauce is watery and runny

Cause: Cut too soon after cooking

Solution: Rest 10 to 15 minutes. The ricotta and meat sauce thicken as temperature drops.

Issue: Pasta is too soft or mushy

Cause: Overcooked or thawed before baking

Solution: Never thaw. Cook from frozen and check doneness at minimum time.

Product Variations and Related Items

Similar Costco Products

• Kirkland Signature Beef Lasagna (Item #1321537) – No sausage, milder flavor profile
• Costco Ravioli Lasagna – Uses cheese-stuffed ravioli instead of flat noodles
• Kirkland Mac and Cheese – Another cheesy Costco prepared meal
• Costco Chicken Alfredo – Creamy pasta alternative

Cooking Time Adjustments

The Beef Lasagna (non-sausage version) cooks at the same time and temperature. If you find the Costco ravioli version, check the package as times differ slightly.

For a complete Italian dinner, pair with Costco meatballs as an appetizer.

Which Method Should You Choose?

Choose Conventional Oven when:

• You want the best texture with crispy cheese top
• Cooking a full 3-pound tray
• You have 70 minutes available
• Feeding 4 to 6 people

Choose Convection Oven when:

• You want good texture with 15 minutes less cooking time
• Your oven has convection mode
• Even browning matters to you

Choose Microwave when:

• Speed is your priority (under 30 minutes)
• Crispy top does not matter
• You need dinner fast on a busy weeknight

Choose Air Fryer when:

• Your air fryer fits the tray or a portion
• You want crispy cheese without heating full oven
• Cooking for 1 to 2 people

Time Comparison

Microwave (25-30 min) is fastest. Air Fryer (35-40 min) comes next. Convection (45-60 min) beats Conventional Oven (60-70 min) by about 15 minutes.

Texture Ranking

Air Fryer and Conventional Oven tie for crispiest top. Convection produces even browning. Microwave gives softest texture with no crisp.

FAQ on How To Cook Costco Lasagna

Do You Need to Thaw Costco Lasagna Before Cooking?

No. Cook the Kirkland Signature lasagna directly from frozen.

Thawing is not recommended. The frozen lasagna goes straight into a preheated oven at 375 degrees F. Thawing can make the pasta layers soggy and affect the final texture.

What Temperature Do You Cook Costco Frozen Lasagna?

Set your conventional oven to 375 degrees F. For convection ovens, use 350 degrees F.

The lower convection temperature works because the fan circulates hot air more efficiently. Both methods produce golden brown cheese and bubbling edges when done properly.

How Long Does Costco Lasagna Take to Cook?

Conventional oven takes 60 to 70 minutes total. Microwave runs 25 to 30 minutes.

Convection oven needs 45 to 60 minutes. Air fryer takes 35 to 40 minutes. Times vary based on your specific appliance.

What Internal Temperature Should Costco Lasagna Reach?

The center must hit 165 degrees F minimum. This is the USDA food safety standard.

Use a food thermometer to check. Insert it into the thickest part of the lasagna. Do not rely on visual cues alone.

Can You Cook Costco Lasagna in the Microwave?

Yes. Microwave on HIGH for 10 minutes, then at 50% power for 14 to 17 minutes.

Cut a 2-inch slit in the plastic film first. The microwave method is fastest but produces a softer texture without crispy cheese.

How Many People Does One Tray of Costco Lasagna Feed?

One 3-pound tray serves 4 to 6 people. The package lists 6 servings per tray.

Each serving is about 1 cup (226g). The twin pack totals 12 servings, making it ideal for large family dinners or meal prep.

Should You Remove the Plastic Film Before Baking?

Keep the film on during the first 50 minutes. Just cut a 2-inch vent slit.

Remove the plastic film after 50 to 55 minutes. This lets the mozzarella topping brown and get crispy during the final 10 to 15 minutes.

How Long Should Costco Lasagna Rest Before Cutting?

Let it rest 5 to 10 minutes after removing from the oven.

Resting allows the ricotta cheese and meat sauce to set. Skip this step and your lasagna falls apart when serving. Ten minutes produces cleaner slices.

Can You Cook Costco Lasagna in an Air Fryer?

Yes, if the tray fits your basket. Start at 250 degrees F for 10 minutes, then 350 degrees F for 25 to 30 minutes.

Oven-style air fryers work better than basket models. Total cooking time runs 35 to 40 minutes with crispy results.

How Do You Store and Reheat Leftover Costco Lasagna?

Refrigerate leftovers within 2 hours. Store in an airtight container for up to 4 days.

Reheat in the microwave for 1 minute, then 30-second intervals. Or bake at 350 degrees F for 20 minutes covered with foil.

Conclusion

Learning how to cook Costco lasagna takes minimal effort. The Kirkland Signature frozen lasagna goes from freezer to table in about an hour using a conventional oven.

Stick to 375 degrees F and check for that 165 degree internal temperature. Let it rest before cutting.

Whether you choose the oven method for crispy cheese or the microwave for speed, this Italian comfort food works for busy weeknight dinners. The twin pack feeds up to 12 people, making it solid for family gatherings or meal prep.

Store leftovers properly and reheat to 165 degrees F for safe eating.