How to Make It
Heat oven to 400°F. Place squash on a parchment-lined rimmed baking sheet, drizzle cut sides with 2 tablespoons of the oil, and season with 1 teaspoon salt, and several grinds pepper. Place cut side down and roast until easily pierced with a fork, 40 to 45 minutes. Increase oven temperature to 450°F.
Meanwhile, combine the ricotta, parsley, basil, red pepper flakes, half the mozzarella, 1½ teaspoons salt, and ¼ teaspoon pepper in a large bowl. In a separate small bowl, combine the breadcrumbs with remaining 1 tablespoon oil and ¼ teaspoon salt.
Using a fork, gently scrape out the squash strands and transfer to the bowl with ricotta mixture. Stir until mostly combined but still streaky. Return the mixture to the hollowed-out squash halves. Dollop the marinara over the squash and scatter with remaining ½ cup mozzarella. Top with Parmesan, and breadcrumbs. Bake until breadcrumbs are golden and cheese is melted and browned in spots, 25-30 minutes. Serve topped with more basil.