Preheat the oven to 425 F. Add squash, onion and garlic to a parchment-lined baking sheet then toss with olive oil, season with salt & pepper to taste, then roast for 25 minutes on the bottom rack of the oven.
Meanwhile, combine all ingredients in a large bowl to make turkey meatballs, then line another baking sheet with parchment paper. Spray with cooking spray or grease with a bit of olive oil, then roll meat mixture into 1-inch meatballs. You should have 16 of them. Bake meatballs on the rack above the butternut squash for 20 minutes.
While squash and meatballs are cooking, cook pasta in a large pot of salted boiling water for 6-7 minutes until al dente, then drain and set aside. Next, grate the cheese for the squash sauce.
Remove squash from the oven and transfer to a blender along with milk and blend until smooth and creamy. Meanwhile, heat the pot that the pasta was boiling in over medium-heat heat.
Add squash mixture to the pot, then stir in orzo and cheeses, stirring to combine and seasoning with salt & pepper to taste if needed. Divide the orzo among 4 bowls and top each bowl with 4 meatballs. Garnish with fresh herbs if desired, then serve and enjoy!