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.
Cooking food for 2 minutes at 50% power gives a noticeable difference in average temperature compared to cooking food for 1 minute at 100% power and waiting a minute.
And I don't always know what it decides to do as far as turning the magnetron on and off on its sensor modes, but it'll spend a while doing automated reheat and potatoes and what not and it'll be dang near perfect every time.
Don't get me wrong I'd love an inverter microwave, truly a better option. But its not like the duty cycle process has no impact.
It's a GE Profile model FWIW. It seems like a good product line from my experiences. The matching oven has also been a good performer overall.
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.