Preheat oven to 350 degrees. Slice squash in half and place fleshside down in a baking dish.
Add 1/4-inch of water. Bake for 40 minutes, or until tender and remove. Rake squash with a fork, creating "spaghetti" strands. Spoon on sauce, mozzarella, and basil. Place back in oven and bake until cheese begins to bubble. Serve warm