Multiple layer toasting in Microwave
Microwaves don't toast.

The pass high energy microwaves through food. These waves struggle to penetrate high density materials, causing them to heat. It's (mostly) the water within the microwaved food that is heated up, and that cooks (or defrosts) your stuff.

Toasting is an external application of usually radiated (but conducted will do) dry heat.

You might be able to heat the oil within the peanuts to the point where they fry... It'd probably work on multiple levels before turning into a smokey mess or combusting. But even then, frying really isn't the same thing as toasting them. 

You want a dry frying pan on a hob, or a grill.