Cut spaghetti squash in half lengthwise, and remove the seeds. Drizzle olive oil on flesh sides and sprinkle with salt and pepper. Place cut side down on a baking sheet and bake for 30-40 minutes, until fork can easily pierce through the skin of the squash. Allow squash to cool, and then remove the "spaghetti" from each half of the squash using a fork. This step can be done ahead of time.
Preheat oven to 350 degrees
In a medium skillet, brown turkey until fully cooked over medium heat. Add spaghetti squash and marinara sauce to the skillet. Stir until all ingredients are well combined.
Next stir in the mozzarella cheese and ½ of the Parmesan cheese to the mixture.
Remove the skillet from the heat and stir in basil. Place the mixture into a 9x9 baking dish and top with remaining parmesan cheese. Bake for 25-30 minutes. Serve with a side salad and dinner is ready.