I have used a microwave
recipe like Lometa
's to make peanut brittle for about 10 Christmas
es. It comes out wonderfully and I give it to everyone who asks as a gift (more each year). I use dry roasted peanuts instead of raw, and omit the salt. I lightly butter my cookie sheet instead of using the foil, non-stick cooking spray, and preheated oven.
Where I would caution anyone who wants to try this recipe is that cooking times for each microwave vary. It takes a lot of trial and error to determine the correct times for making suitable brittle, especially when you don't know what you're trying to attain. Have a lot of ingredients on hand; be prepared to make a number of batches until you get it right. Also, be prepared for a mess. It is a lot of work to clean up the "not quite" batches, and really hot water is always required for cleaning your microwaving dish and spatulas.
When you've got it perfected, it is the best peanut brittle! I have also made cashew brittle, which is absolutely delicious, the same way.
Cooking times in my current microwave: 3:45; 3:15; 1:15.