Preheat oven to 375F. Cook ground beef until almost fully browned then add onion, garlic, red pepper, salt, and pepper and finish browning.
Stir in tomato paste and oregano and cook for 2 more minutes. Stir in crushed tomatoes. (May omit these 3 ingredients and use a low-carb jar of spaghetti/marinara sauce instead. Reduce heat to medium low and simmer for 15 minutes. Remove from heat. Pour meat sauce over the cauliflower and stir to combine.