Spaghetti squash is a winter squash that separates into spaghetti-like strands when cooked. Roasted until tender and topped with tomato sauce and Parmesan cheese, it makes a simple, comforting dish that's a delicious way to enjoy this seasonal vegetable.
Preheat the oven to 400°F. Line a baking sheet with parchment paper.
Carefully cut the spaghetti squash in half lengthwise. Scoop out the seeds and stringy center with a spoon.
Brush the cut sides with olive oil and sprinkle with salt and black pepper. Place the squash halves cut-side down on the baking sheet.
Roast for 35–45 minutes, until the squash is tender and easily pierced with a fork. Avoid overcooking, as the strands may become mushy.
While the squash roasts, warm the marinara sauce in a small saucepan over medium-low heat.
Let the squash cool for a few minutes. Use a fork to gently scrape the flesh into spaghetti-like strands, leaving the strands inside the squash shells or transferring them to a serving bowl.
Spoon the warm tomato sauce over the squash. Sprinkle with Parmesan cheese, red pepper flakes, and fresh basil or parsley, if using. Serve warm.