Flour tortillas spread with just a smidgen of pizza sauce --(You could use more sauce if you like.) Olives, mushrooms. (or whatever toppings you like) Mozarella cheese.
Bake at 400 degrees for about 15-20 minutes -- Keep your eye on it as it bakes. I have an oven with several rack positions, so I had mine about the third rack down -- higher than in the middle but not so high as you would if you were broiling something.
That's it. I borrowed the idea from my mother-in-law.