Carefully cut the spaghetti squash in half and scoop out the seeds. Drizzle with olive oil, salt, and pepper. Place cut-side down on a prepared baking sheet and bake at 400F for 30-45 minutes, until tender.
Remove from oven, let cool slightly, then use a fork to scrape the squash into long spaghetti-like strands.
Meanwhile, warm homemade or store-bought marinara sauce in a saucepan on the stove.
Transfer spaghetti squash strands to a large bowl, toss with desired amount of marinara sauce. Top with chopped fresh basil and a little extra salt and pepper, to taste. Enjoy!