Keep frozen. After thawing, store in the refrigerator and consume within 5 days. Heating instructions: To reduce heating times, transfer the food from the freezer to the refrigerator one day in advance. Oven 1. Preheat the oven to 350 °F. 2. Take the portion you prefer to heat and set aside the rest for future use. 3. Place the food in a resistant tray, and cover with aluminum foil. 4. Heat for 40 minutes. Microwave 1. Take the portion you prefer to heat and set aside the rest for future use. 2. Transfer the lasagna to a microwave-safe container. 3. Cover the container with a microwave-safe lid or microwave safe plastic wrap. Leave a small vent for steam to escape. 4. Heat for 8 - 10 minutes if frozen or 5 -7 minutes if thawed. Do not use an aluminum tray in the microwave. Heating times may vary based on appliance.