Preheat oven to 400 degrees. Halve spaghetti squash and place cut side down on buttered baking sheet. Bake for 40 minutes or until tender. Cool to the point of being able to handle, remove and discard seeds then shred pulp gently with a fork so that strands resemble spaghetti noodles. Reduce oven temperature to 350 degrees.
While squash bakes, cook and crumble bratwurst in a skillet over medium heat. Add peppers, onion and garlic and continue cooking until vegetables are crisp tender.
Add squash, tomatoes, basil, oregano, salt and pepper to skillet and heat through. Remove from heat and drain excess liquid. Mix in 3/4 cup Parmesan and transfer to a greased 9×13 or oval 2 quart casserole dish. Bake uncovered for 30 minutes, topping with remaining Parmesan for the last five minutes of baking time.