Prepare the spaghetti squash in the oven or microwave. To roast, preheat the oven to 375 degrees. Cut the squash in half and scoop out the seeds. Spray with cooking spray and place on a baking sheet covered in foil. Bake for 45-60 minutes until tender. To microwave pierce the squash all over with a knife or fork. Cook each squash whole for 10-12 minutes until tender. Carefully cut in half and remove seeds. Scrape the squash away from the skin using a fork.
Heat the olive oil over medium high heat. Add the sausages and cook for 6-8 minutes until browned on both sides. Add the cherry tomatoes, garlic, and Italian seasoning. Cook for 3-5 minutes or until desired doneness. Sometimes I prefer the tomatoes more raw and sometimes I cook them longer so they burst and release all the juices.
Add the squash and toss to combine. Season with salt and pepper. Add back to the spaghetti squash halves if desired. Top with basil.