Preheat the oven to 400°F. Line a baking sheet with parchment.
Carefully cut the squash in half lengthwise. If cutting is tough, microwave the whole squash for 3 to 4 minutes to soften the skin. Scoop out the seeds.
Rub the cut sides with olive oil, then season with salt and pepper. Place halves cut-side down on the lined sheet.
Roast 35 to 45 minutes until a fork slides in easily and the strands pull apart. Pull earlier if your oven runs hot to avoid mushy strands.
Let sit for 5 minutes. Use a fork to scrape the flesh into “noodles.”
Bolognese
In a large skillet, warm 1 to 2 tablespoons olive oil over medium heat.
Add diced onion and cook until softened, about 5 minutes. Add garlic and cook 30 seconds. Add the chopped zucchini and carrot and continue cooking, stirring to keep from sticking, for an additional 5 minutes.
Crumble in ground beef. Season with salt and pepper. Cook until browned and caramelized, about 7 to 8 minutes.
Stir in tomato paste and cook 1 to 2 minutes to caramelize and deepen the sauce.
Pour in crushed tomatoes. Bring to a gentle simmer and cook 15 to 20 minutes, stirring now and then, until thick and glossy.
Stir in chopped fresh basil. Taste and adjust salt and pepper.
Serve
Divide squash strands among 4 bowls. Spoon the hot bolognese over the top.
Finish with grated Parmesan and more basil if you are not doing Whole30. For dairy-free, drizzle extra-virgin olive oil and nutritional yeast. Add red pepper flakes for gentle heat.
Notes
Always read labels on tomato paste and crushed tomatoes to avoid hidden sugars.
No fresh basil? Use 1 teaspoon dried Italian seasoning or 1/2 teaspoon dried basil.
Spread spaghetti squash strands on a clean towel or paper towels for a minute to drain. This keeps bowls from getting watery.
Faster sauce: Use a quality no sugar added marinara in place of crushed tomatoes and tomato paste on busy nights.
Store cooked squash strands and sauce in separate airtight containers. Refrigerate up to 4 days.
Reheat the sauce on the stove over medium heat until hot and thick.
Warm squash gently in a dry skillet over low to medium heat to steam off extra moisture. Stir a few times until heated through.
Freeze the bolognese sauce up to 3 months. Thaw in the fridge, then simmer to revive flavor. Do not freeze cooked squash, it turns soft and watery after thawing.
Assemble bowls right before eating for the best texture.