Preheat oven to 425°.
Unroll pizza dough onto a large baking sheet coated with cooking spray; fold under edges of dough to form an 11-inch circle. Bake at 425° for 7 minutes; set aside.
Preheat oven to 500°.
Combine thyme and next 8 ingredients (thyme through onion) in a bowl; toss well. Place vegetable mixture in a 13 x 9-inch baking dish. Bake at 500° for 15 minutes, stirring halfway through cooking time.
Reduce oven temperature to 425°. Sprinkle half of cheese over prepared pizza crust. Arrange roasted vegetables over cheese, and top with remaining half of cheese. Bake at 425° for 12 minutes or until crust is lightly browned.