01 - Preheat oven to 375°F and lightly grease a 9x13-inch baking dish.
02 - Boil pasta in salted water until al dente, then drain and set aside.
03 - Cook ground turkey in a large skillet over medium heat until browned, about 6-7 minutes, breaking up meat with a spoon.
04 - Add onion, garlic, and bell pepper to the skillet; cook for 4-5 minutes until softened.
05 - Stir in spinach and cook for 1 minute until wilted.
06 - Add marinara sauce, tomato paste, Italian seasoning, red pepper flakes, salt, and pepper; simmer for 3-4 minutes.
07 - Mix cooked pasta with turkey sauce and half the mozzarella and Parmesan cheeses.
08 - Transfer mixture to prepared dish and top with remaining mozzarella and Parmesan.
09 - Bake uncovered for 20-25 minutes until cheese is melted and bubbly.
10 - Let rest for 5 minutes, then garnish with basil or parsley before serving.