Preheat oven to 350°F.
Heat olive oil in pot or skillet over medium-high heat. Add sausage, beef, peppers, onion, garlic, and seasonings. Cook, stirring occasionally, until meat is browned; about 5 minutes. Remove from heat.
Stir in the riced cauliflower and drained tomatoes.
Spread mixture evenly into a 9x13-inch casserole pan. Top with sliced mozzarella.
Bake at 350°F for 25 to 30 minutes or until cheese is beginning to brown. If needed, the casserole can be placed under the broiler for a minute or two to brown the cheese quickly.
