01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - In a large bowl, combine ground turkey, breadcrumbs, egg, parsley, garlic, onion powder, salt, and pepper. Mix until just combined.
03 - With damp hands, form the mixture into 20–24 meatballs. Place on the prepared baking sheet.
04 - Bake meatballs for 15–18 minutes, or until cooked through and lightly browned.
05 - While meatballs bake, heat olive oil in a large skillet over medium heat. Add onion and cook until softened, about 3 minutes.
06 - Add mushrooms and cook until browned and their liquid has evaporated, about 5–7 minutes. Stir in garlic and cook for 1 minute more.
07 - Sprinkle flour over the vegetables, stirring to coat. Cook for 1 minute.
08 - Slowly pour in chicken broth, stirring constantly to avoid lumps. Add Worcestershire sauce and Dijon mustard. Bring to a simmer and cook until slightly thickened, about 3–4 minutes.
09 - Reduce heat to low. Stir in sour cream until smooth. Season with salt and pepper to taste.
10 - Add the baked meatballs to the skillet and simmer gently for 3–4 minutes, turning to coat in the sauce.
11 - Serve meatballs and sauce over cooked egg noodles. Garnish with chopped parsley.