Wash and slice the sausage, onions, and green peppers.
Spray crockpot with Nonstick Spray. Add sausage, sliced peppers, onions, diced tomatoes, tomato sauce, Italian seasoning, garlic to the crockpot. Stir to mix everything together. Turn crockpot on high for 6 hours, stir occasionally while it cooks.
About an hour before the crockpot sausage and peppers is done preheat oven to 375 degrees.
Cut the spaghetti squash in half and scoop out the seeds with a spoon.
Lay skin side down on a rimmed sheet pan that is lined with aluminum foil.
Bake for 45 mins or until cooked to a touch with a fork. Once the squash is cooked scrape the flesh with a fork to create noodles and place the spaghetti squash noodles into a large mixing bowl.
Add the sausage, peppers and onions mixture into the noodles and stir until combined. Place the mixture back into the squash shells and top with the provolone cheese slices.
Place the squash under the broiler until the cheese is melted.