Preheat oven to 425 degrees Grease parchment paper and place on a medium-size baking sheet.
Drain moisture from riced cauliflower. If using frozen cauliflower, thaw in the microwave first. Using a towel or paper towel to press moisture out works well.
Put riced cauliflower into a large mixing bowl. Add egg, basil, oregano, garlic salt, parmesan cheese, and mozzarella cheese to the bowl and mix well.
Evenly press mixture onto the parchment paper; the mixture should nearly cover the entire baking sheet.
Bake for about 15 minutes, flipping halfway through, until edges start to brown. When flipping, it helps to have a second piece of parchment paper to flip the crust onto then slide back onto the baking sheet.
Top with your favorite pizza toppings, reduce the oven temp to 350 degrees F, and bake for an additional 10 minutes, until the cheese has melted.