- - 2 medium spaghetti squash (about 5 pounds total)
- - 1 tablespoon olive oil
- - 1 teaspoon kosher salt
- - ½ teaspoon freshly ground black pepper
- - 4 cloves garlic, smashed
- - 1 cup marinara sauce
- - 1/4 cup finely grated Parmesan cheese (about 1 ounce)
- - ¼ cup torn fresh basil leaves, plus more for garnish
- - ¼ teaspoon red pepper flakes
- - 12 ounces precooked meatballs [about 12 (1 ½-inch) meatballs], thawed if frozen
- - ¾ cup whole-milk low-moisture shredded mozzarella cheese
- Arrange a rack in the middle the oven and heat to 400°F. Line a rimmed baking sheet with aluminum foil; set aside.
- Cut each squash in half lengthwise and scoop out the seeds. Brush the cut sides of each squash with the oil and season with the salt and pepper. Place cut-side down in a single layer on the baking sheet, placing one garlic clove under each piece of squash. Roast until the squash are soft when poked with a fork and the skin is browned and blistered, about 40 minutes.
- Remove the baking sheet from the oven. Flip the squash over with tongs and remove and discard the garlic. Use a fork to shred the inside of each squash half, leaving about 1/2 inch of unshredded squash left in the shell. Transfer the shredded squash to a large bowl. Add the sauce, Parmesan, basil, and red pepper flakes and stir to combine.
- Evenly divide the shredded filling between the squash halves. Divide the meatballs over the filling, then top with the mozzarella cheese.
- Bake until the meatballs are heated through and the cheese is melted, 15 to 20 minutes. Garnish with more fresh basil before serving.