Preheat oven to 375 degrees F. On a large baking sheet, rub insides of spaghetti squash with olive oil and season with salt and pepper Place halves, cut sides down, in a baking dish. Bake for 40 minutes.
How to make stuffing
Meanwhile, heat a large skillet, add olive oil, sausage, garlic, parsley and seasoning and cook for about 10 minutes until sausage is fully cooked. Add green onions, tomatoes, and continue cooking for 5 more minutes. When ready, set aside.
How to stuff spaghetti squash
Once squash is cooked and cool enough to handle, use a fork to carefully rake up pulp to separate it into strands, leaving the strands in the shells. Place squash halves on a baking sheet and spoon the filling into squash shells. Sprinkle with Parmesan cheese.
Bake for 20 minutes at 375 degrees F until filling is heated through and cheese is melted