Bring a large pot of water to boil. Cut the squash lengthwise into two halves and scoop out the flesh with a spoon. Keep the scooped out squash aside to use later. Using a wooden spoon, put the squash gently into the boiling water and let it cook for a couple of minutes.
Then, in a skillet, add olive oil and warm it. Add the garlic and onion and stir till softened. Next, add the tomatoes and scooped out squash. Sauté for ten minutes. You can now add the Italian sausage and cook it till brown. Add salt, pepper, and the Italian seasoning.
Preheat the oven to 350°F. Grease a 13 x 9 baking dish with olive oil or cooking spray.
Place the squash skin down in the baking dish. Spoon the sausage mixture into the squash boats evenly. Top them with the shredded cheese and sprinkle Parmesan cheese. Bake for 30-35 minutes till the cheese melts and the squash is fork-tender.
Sprinkle parsley on top, if desired. Enjoy this summer special!
You can substitute the tomato for 1/2 cup bell pepper or 1/2 cup spinach for a different flavor.