Preheat oven to 450°.
Roll the dough into a 12-inch circle on a lightly floured surface. Place the dough on a 12-inch pizza pan or a baking sheet coated with cooking spray and sprinkled with cornmeal. Crimp the edges of the dough with your fingers to form a rim.
Heat the oil in a large nonstick skillet over medium heat. Add mushrooms and onion; sauté for 5 minutes. Cover, reduce heat to medium-low, and cook for 3 minutes or until the onion is very tender. Stir in the salt and pepper.
Spread the sour cream over pizza crust, leaving a 1-inch border. Top with mushroom mixture; sprinkle with cheese. Bake at 450° for 15 minutes or until lightly browned. Cut into 8 wedges.