Preheat oven to 450 degrees F. Place pizza stone on the bottom rack of the oven. Combine tomatoes, onion, garlic cloves, salt, pepper flakes, and sugar. Toss tomato mixture with olive oil; roast 25-30 minutes until tomatoes have softened and become lightly caramelized.
Add a thin layer of basil pesto and top with roasted tomatoes.
Sprinkle with parmesan cheese and mozzarella or provolone.
Place on parchment paper and bake on stone.
Bake for 5-6 minutes or until cheese is bubbly and edges are crisp.