How to Make It
Preheat oven to 350°.
Cut each squash in half lengthwise. Scoop out seeds; discard. Place squash halves, cut sides up, on a baking sheet. Bake at 350° for 50 minutes. Let stand 10 minutes. Scrape inside of squash with a fork to remove spaghetti-like strands. Place strands on a clean dish towel; squeeze until barely moist.
Heat a large skillet over medium-high heat. Add oil to pan; swirl to coat. Add garlic; cook 30 seconds. Add spinach; cook 1 minute or until spinach wilts. Remove from heat. Combine spinach mixture, squash strands, ricotta cheese, salt, and half of mozzarella cheese in a medium bowl.
Return skillet to medium-high heat. Add turkey to pan; cook 4 minutes or until browned, stirring to crumble. Add marinara sauce; cover, reduce heat to medium, and simmer 4 minutes. Remove from heat.
Increase oven temperature to 425°.
Spoon sauce evenly into the bottom of each squash half. Top evenly with squash mixture. Sprinkle evenly with remaining mozzarella cheese and Parmesan cheese. Bake at 425° for 20 minutes.
Preheat broiler to high (keep squash in oven). Broil squash 1 to 2 minutes or until cheese is golden brown and bubbly. Remove from oven; let stand 10 minutes.