How long to bake a frozen lasagna at 425 instead of 400?

You should not attempt to bake a frozen lasagna at 425 degrees Fahrenheit (218 degrees Celsius) even if the original recipe calls for 400 degrees Fahrenheit (204 degrees Celsius).

Frozen lasagna is typically thawed before baking to ensure even cooking and to prevent the center from remaining frozen while the edges become overcooked. Rapid thawing at high temperatures, like 425 degrees Fahrenheit, can cause uneven cooking and potential safety hazards due to incomplete thawing.

It's always recommended to follow the thawing and baking instructions provided in the original recipe or on the product packaging to achieve the best and safest results.