In a large bowl, mix together zucchini slices, garlic, oregano, red pepper flakes, salt, and olive oil. Arrange slices in a single layer on a baking sheet. Roast for 25-30 min, until soft. (The roasted zucchini can be made ahead of time and refrigerated until ready to use.)
Spread a thin layer of pesto over your pizza crust. Top with cheese, tomato slices, and roasted zucchini.
Bake pizza on a baking sheet or pre-heated pizza stone for 5-7 minutes, or until cheese is melted and starting to brown.
Remove from oven and let set 2-3 minutes before serving.