- Preheat oven to 400ºF. Cut each squash into 1-1/2-inch-thick rings; remove seeds. Arrange on 2 rimmed baking sheets lined with parchment paper. Drizzle with 2 tablespoons oil. Season to taste with salt and pepper. Bake 40-45 minutes or until fork-tender. When cool enough to handle, cut through one section of each ring to peel and discard tough skins. Separate fibers to create long stands.
- Heat remaining oil in large skillet on medium-high heat. Add sausage and red pepper flakes; cook 5-7 minutes or until browned. Add onions, bell peppers and garlic; cook 3-4 minutes or until crisp-tender. Add tomatoes, squash strands and sauce. Cook 1-2 minutes or until heated through, gently mixing until combined.
- Sprinkle with cheese and basil before serving.
Plant-based meatless or vegetarian Italian sausage is available in the refrigerated meat section or frozen aisle of a well-stocked grocery store.
Cutting the spaghetti squash into rings results in faster cooking and guarantees longer squash strands.