1. Remove dough from refrigerator. Let stand at room temperature, covered, 30 minutes.
2. Place a heavy baking sheet in oven. Preheat oven to 500° (keep baking sheet in oven as it preheats).
3. Heat a large nonstick skillet over medium heat. Add 1 teaspoon oil to pan; swirl to coat. Add onion; cook 4 minutes or until softened, stirring frequently. Remove onion from pan. Add 1 teaspoon oil to pan; swirl to coat. Add garlic; cook 1 minute, stirring frequently. Add tomatoes, 1 tablespoon oregano, pepper, and salt; cook 4 minutes or until most of liquid evaporates, stirring mixture occasionally.
4. Roll dough into a 13-inch circle on a lightly floured surface; pierce entire surface liberally with a fork. Carefully place dough on preheated baking sheet. Spread tomato mixture evenly over dough, leaving a 1/2-inch border. Top with onion and cheeses. Bake at 500° for 12 minutes or until crust is golden and cheese is lightly browned.
5. Heat a large nonstick skillet over medium-high heat. Add remaining 1 teaspoon oil to pan; swirl to coat. Add spinach; sauté 2 minutes or until spinach wilts. Top pizza with remaining 1 tablespoon oregano and spinach. Cut into 8 slices.