Physics does not apply to lasagna.
Also I suck at making lasagna.
(I also imagine using the circulation in a convection oven might help as well. Also, preheating your oven! Even if it's a toaster oven.)
Use the power button to select a lower power level, and cook the food for longer.
Most people think they should be able to put food in, nuke it at full power for as short of a time as possible, and then immediately shove it in their face with no consequence and we all know that doesn't work yet most of us will keep doing it anyways.