How to Make It
Preheat oven to 375°.
Place half of cauliflower in a food processor; pulse 10 to 15 times or until finely chopped (like rice). Transfer cauliflower to a baking sheet lined with parchment paper. Repeat procedure with remaining cauliflower. Coat cauliflower with cooking spray. Bake at 375° for 25 minutes, stirring once. Cool.
Increase oven temp to 450°.
Heat a large skillet over medium-high heat. Add 1 teaspoon oil to pan; swirl to coat. Add mushrooms and bell pepper; sauté 5 minutes or until tender. Set aside.
Place cauliflower in a clean kitchen towel. Squeeze until very dry. Combine cauliflower, remaining 1 teaspoon oil, 1/4 cup basil, 1/8 teaspoon black pepper, salt, garlic, 2 ounces mozzarella cheese, egg whites, and Parmesan cheese in a bowl. Press cauliflower mixture into 2 (8-inch) circles on a baking sheet lined with parchment paper. Coat crusts with cooking spray.
Bake crusts at 450° for 22 minutes or until browned. Remove pan from oven; top crusts evenly with mushroom mixture, tomatoes, spinach, remaining 1/4 cup basil, remaining 1/8 teaspoon black pepper, and remaining mozzarella cheese. Bake an additional 7 minutes or until cheese melts.