Preheat oven to 375°F. Quarter and remove the seeds from your spaghetti squash. Be sure to remove any vendor stickers from the outside!
Place squash in a baking dish inside facing up. Drizzle with olive oil and season with salt & pepper. Flip squash over and place in oven to roast for 1 hour.
While squash roasts, crumble & brown sausage over medium heat in a pot. Drain excess fat, then add garlic, marinara, tomato sauce, paste, & fire-roasted tomatoes. Stir, cover, & simmer for ~30 min.
After an hour, remove squash from oven & flip the inside facing up. Top each squash piece with 1/2 cup of meat sauce.
If desired, top with mozzarella cheese and melt under the broiler.
Enjoy with a cold beer or cider!