Cut squash in half lengthwise. Scoop out seeds; discard. Place squash halves, cut sides down, on a baking sheet coated with cooking spray. Bake at 350° for 1 hour or until tender.
Heat oil in a medium saucepan over medium heat. Add garlic; cook 3 minutes, stirring occasionally. Add tomatoes; bring to a simmer. Cook for 15 minutes or until thickened. Remove from heat; stir in 1/3 cup basil.
Cool squash at room temperature for 10 minutes or until cool enough to handle. Scrape inside of squash with a fork to remove spaghetti-like strands to measure about 5 cups. Divide squash evenly among 6 plates; top each serving with about 1/3 cup sauce and 1 tablespoon cheese. Top with remaining basil.
This was my first experience with spaghetti squash, and I think I'm hooked. This is actually super-easy and simple, and it is so healthy and different. I did add a pinch of salt to the tomato sauce, and I added some chicken sausage to the final product (not mixed in the sauce) to add a little heft. The recipe does stand on its own, though. One mistake I made was to simply mix all the squash with all the sauce before serving, and I would follow the recipe's instructions and top the squash with the sauce per serving.