Combine the breadcrumbs and milk in a large mixing bowl. Stir and let sit for about 5 minutes, until the breadcrumbs have absorbed the milk.
Add egg, Parmesan, grated onion, garlic, soy sauce, 1 tablespoon olive oil, Italian seasoning, garlic powder, onion powder, black pepper, salt, and parsley. Stir until well combined.
Add the ground turkey and gently mix just until everything is evenly combined. Don't overmix.
Scoop and gently shape the mixture into 1½-inch meatballs. You should get about 24-26 meatballs. I like to use a cookie scoop for this part to get even sizing.
Heat 1 tablespoon olive oil and 2 tablespoons butter in a large skillet over medium to medium-high heat. Once the butter is melted and foamy, add the meatballs.
Brown for 1-2 minutes on several sides, turning gently. They don't need to be cooked through.
Pour the marinara sauce around the meatballs. Reduce the heat to low, cover, and gently simmer for 10-15 minutes, or until the centers of the meatballs reach 165°F.
Serve over spaghetti with plenty of sauce and additional Parmesan cheese, if desired.