Preparing the Spaghetti Squash

1. Preheat Oven: Start by preheating your oven to 400°F (200°C).
2. Cut and Clean: Carefully cut the spaghetti squash in half lengthwise using a sharp knife. Scoop out the seeds and stringy pulp from the center.
3. Season: Drizzle the inside of each half with olive oil and sprinkle with salt and pepper.
4. Roast: Place the squash halves cut-side down on a baking sheet lined with parchment paper. Roast in the preheated oven for about 35-45 minutes, or until the flesh is tender and easily pierced with a fork.
5. Shred: Once cooked, remove the squash from the oven. Use a fork to gently scrape out the strands of squash, resembling spaghetti. Set aside.

Making the Tomato Sauce

1. Sauté Onions and Garlic: In a large saucepan, heat olive oil over medium heat. Add the chopped onion and sauté until translucent, about 5 minutes. Stir in the minced garlic and cook for an additional minute.
2. Add Tomatoes: Pour in the crushed tomatoes and tomato paste, stirring to combine.
3. Season: Add the dried oregano, dried basil, sugar (if using), salt, and pepper. Stir well to incorporate the flavors.
4. Simmer: Reduce the heat to low and let the sauce simmer for about 20-30 minutes, stirring occasionally. This allows the flavors to meld together beautifully.
5. Taste and Adjust: Taste the sauce and adjust seasoning as needed. If you prefer a smoother sauce, you can use an immersion blender to puree it to your desired consistency.

Combining the Squash and Sauce

1. Mix Together: In a large serving bowl, combine the cooked spaghetti squash strands with the tomato sauce. Toss gently until the squash is well-coated with the sauce.
2. Garnish: Garnish with fresh basil leaves if desired.