Preheat oven to 400 degrees. Line a baking sheet with parchment paper. With a sharp chef's knife, trim the very top and bottom of the squash. Then, cut it in half widthwise. This allows for a more spiral effect once fully cooked. Scoop out the seeds and stringy insides. I like to use a serrated grapefruit spoon for this task.
Drizzle each side with just a bit of olive oil, too much will make it soggy. Then sprinkle evenly with salt and pepper. Place halves face down on the baking sheet and roast for 30 - 40 minutes. The squash should be just fork-tender on the inside and lightly browned on the outside. The skin will give a little when pressed on the outside but be careful since it's going to be hot! Once done, remove from the oven and flip over.
Let cool for a minute or two so you can handle the squash. While the squash is cooling, warm your favorite Jar Goods sauce over medium heat. Using a fork, scrape the squash into spaghetti-like strands. Add to a bowl, top with the warm sauce and grated parmesan cheese and serve.