Cook bacon in large skillet until crisp; transfer to paper towels to drain. Discard all but 2 tablespoons bacon drippings. Add ground beef, onion, garlic, crushed red pepper, salt and pepper; cook until beef is browned and onions are soft. Drain excess drippings; discard. Stir pasta, bacon, mayonnaise, sour cream, tomatoes, spinach and cheese into skillet.