01 - In a large mixing bowl, blend ground turkey, breadcrumbs, eggs, milk, minced garlic, grated onion, kosher salt, black pepper and chopped parsley until just incorporated.
02 - Form mixture into 32 small, even meatballs and arrange on a parchment-lined tray.
03 - Heat olive oil in a large skillet over medium-high heat. Add diced onion and sauté until translucent, about 3 minutes. Stir in sliced mushrooms, minced garlic, smoked paprika, and dried thyme; cook until mushrooms lose their moisture and soften, about 5 minutes.
04 - Place sautéed vegetable mixture in the slow cooker. Sprinkle flour over the mixture, then pour in chicken broth while whisking until the flour is fully dissolved.
05 - Gently nestle meatballs into the sauce in a single layer. Cover and cook on low for 5 to 6 hours or on high for 2.5 to 3 hours, until meatballs are thoroughly cooked and tender.
06 - In a medium bowl, whisk together sour cream and Greek yogurt. Gradually incorporate 240 milliliters of the hot cooking liquid from the slow cooker into the dairy mixture to temper, then stir the tempered mixture back into the slow cooker. Mix until the sauce is creamy and well-combined.
07 - In the final 20 minutes of cooking, prepare egg noodles according to the manufacturer’s instructions. Drain well.
08 - Ladle meatballs and sauce over hot noodles. Garnish with chopped parsley and serve immediately.