Preheat oven to 400°F. Place squash on a foil-lined baking sheet, drizzle cut sides with olive oil (1 Tbsp. per squash half), and season with salt and pepper. Place cut side down and roast until easily pierced with a fork, 35-40 minutes.
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. Return the mixture to the hollowed-out squash halves. Dollop the marinara over the squash and scatter with remaining mozzarella. Top with grated parmesan and breadcrumbs.
Bake until breadcrumbs are golden and cheese is melted and browned in spots, 25-30 minutes. Serve topped with more basil.
Recipe adapted from: www.realsimple.com