Cook frozen lasagna in an oven preheated to 400 degrees Fahrenheit for 1 1/2 to 2 hours, or until it is heated throughout. Bake it covered for most of the cooking time, removing the cover at the end to allow the top to become golden and bubbly.
- Preheat the oven
Position the oven rack to the center of the oven. Preheat the oven to 400 degrees Fahrenheit.
- Prepare the frozen lasagna
Remove the lasagna from the freezer, and unwrap it. If the lasagna is not already in a baking dish, lightly grease an oven-safe baking dish, and place the frozen lasagna inside.
- Cover the baking dish
Spray aluminum foil with cooking spray, or lightly oil it to help prevent sticking. Cover the dish with foil. Place the baking dish on a baking sheet to catch any sauce that bubbles over.
- Bake it
Bake frozen lasagna for approximately 1 1/2 hours. Take the foil off the baking dish and bake for another 30 minutes or until the top is lightly browned and bubbling.
- Take it out of the oven
Use potholders or oven mitts to remove the lasagna from the oven. Let it sit for 10 to 15 minutes before cutting it into pieces and serving.