Make the Filling: While the squash is baking, combine olive oil, garlic, onions, and bell peppers in a medium-sized skillet over medium heat. Sauté for 3-4 minutes. Push vegetables to the side of the skillet and add ground beef. Cook beef over medium heat for 6-8 minutes, or until meat is cooked through. Add spaghetti sauce, Italian seasoning, salt and pepper. Stir until combined. Reduce heat to low, cover and simmer for 5 minutes.
2-3 Tbsp. oil, 2 cloves garlic, 1 small sweet onion, 1 small green bell pepper, 1 lb. ground beef, 24 oz. spaghetti sauce, 2 tsp. Italian seasoning, ¼ tsp. pepper, 1 tsp. salt