Preheat the oven to 350°F
Cover the lasagna with foil
Place it in an oven-safe dish if needed
Heat for 20 to 30 minutes
Remove the foil for the last 5 to 10 minutes if you want the top crisp
Check that the center is hot before serving
Let it rest for a few minutes before cutting
Reheat single slices in the microwave for 1 to 2 minutes
Add a little water or sauce before microwaving to keep it moist
Cover the slice while microwaving to prevent drying out