Preheat the oven to 400°F (200°C).
Cut the spaghetti squash in half lengthwise and scoop out the seeds.
Drizzle the cut sides with 1 tablespoon of olive oil and place face down on a baking sheet. Roast for 40-45 minutes.
While the squash is roasting, heat 1 tablespoon of olive oil in a large skillet over medium heat.
Add the bell pepper, zucchini, yellow squash, and cherry tomatoes. Cook until tender, about 5-7 minutes.
Add the garlic, oregano, basil, salt, and pepper. Cook for another 2 minutes.
Once the squash is done, use a fork to scrape out the strands.
Toss the squash strands with the cooked vegetables. Serve with grated Parmesan if desired.