1. Scrape seeds out of squash with a spoon. Place squash cut-sides-down in a microwave-safe baking dish. Fill baking dish with 1/2-1 inch of water.
2. Microwave on high for about 15 minutes, or until you can easily pierce the squash with a fork. (Cooking times may need to be adjusted depending on the size of the squash and the power of the microwave being used.)
3. Meanwhile, bring sauce to a simmer in a skillet or sauté pan. Grate garlic directly in sauce and stir to combine. Taste sauce, salt and pepper to taste, adjust heat to low.
4. Once squash is done allow to cool until able to handle, about 15 minutes.
5. Use a fork to scrape out the spaghetti-like strands, and place in colander. Allow to drain a bit. Add spaghetti strands to warm sauce in pan and toss to coat. Add grated parmesan and toss to combine.
6. Optional: Garnish with additional Parmesan, chopped fresh Italian parsley and/or basil.