Preheat oven to 350ºF. Poke spaghetti squash all over with a knife and cook in the microwave for eight to 12 minutes until soft. If you don’t have a microwave, place the poked squash on a baking pan and bake at 375ºF for 45 to 60 minutes.
While the squash is cooking, add oil, yellow pepper, red onion, carrots, zucchini, garlic, Italian seasoning red oregano crushed red pepper, and salt to a pan. Cook over medium heat for about 10-15 minutes or until fully cooked through.
Place the spaghetti squash flesh in a casserole dish. Add the cooked veggies, pasta sauce, and half of the cheese and mix well. Sprinkle the other half of the cheese on top and bake for 30 minutes or until the cheese is bubbly.