Place the cauliflower in a food processor. Cover and pulse four to six times or until crumbly and mixture resembles the texture of couscous.
Place a pizza stone or baking sheet in the oven. Preheat oven to 425°F. Place cauliflower in a microwave-safe casserole with 2 tablespoons water. Microwave, covered, on 100% power (high) for 3 to 4 minutes or until tender, stirring once or twice. Cool. Transfer cauliflower to a 100% cotton flour-sack towel. Wrap towel around cauliflower and squeeze until there is no more liquid (this step is critical).
In a medium bowl stir together cooked and drained cauliflower, egg, the 1/4 cup Italian cheese blend, the Parmesan cheese, panko, Italian seasoning, and salt. On a piece of parchment paper pat cauliflower mixture into a 12-inch circle. Transfer crust on paper to the preheated pizza stone. Bake for 12 to 15 minutes or until crisp and starting to brown.
Meanwhile, in a large skillet cook and stir mushrooms, sweet pepper, and onion in hot oil for 4 to 6 minutes or until crisp-tender. Remove from heat.
Spoon pizza sauce over baked crust, spreading evenly. Top with cooked vegetables. Sprinkle evenly with the 1 cup Italian cheese blend. Bake about 5 minutes more or until heated and cheese melts. If desired, sprinkle with snipped fresh herb. Cut into slices to serve.
In a small saucepan, cook onion and garlic in hot oil over medium heat about 5 minutes or until onion is tender, stirring occasionally. Stir in tomato sauce, oregano, basil, salt, and crushed red pepper. Bring to a boil; reduce heat. Simmer, uncovered, about 5 minutes or until sauce reaches desired consistency. Makes 1 cup.