Preheat oven to 350 degrees F.
Slice the spaghetti squash in half and place cut side down a baking sheet. Bake for 30 minutes or until tender when pierced with a knife.
Meanwhile, remove sausage from casings and form small meatballs about the size of a quarter. Heat a heavy nonstick pan over medium-high heat and add olive oil. When oil is hot, add meatballs and cook until browned on all sides. Add tomatoes, olives, capers, and garlic and simmer for 15 minutes. In the last minute of cooking, add basil.
While sauce is simmering, scrape out the inside of the squash with a fork into a large bowl; set aside.
Toss sauce and squash together and top with Parmesan. Serve immediately.