Flour or corn tortillas
Any kind of cheese, such as american or mozzarella.
Depending on whether you are shredding cheese or using presliced "kid cheese", put a thin layer about 1/4-1/2 inch thick on tortilla. Top with another tortilla. Zap in microwave for about a minute, let cool. Cut like a pizza into triangles.
Variation: you can sneak veggies (or cooked meats) into this tortilla by shredding them along with the cheese. I have managed to get my oldest to eat broccoli and carrots this way...:)