Step 1: In a large bowl, gently combine ground beef, breadcrumbs, milk, beaten egg, garlic powder, onion powder, salt, and pepper. Do not overmix. Roll the mixture into approximately 20-24 meatballs, about 1.5 inches in diameter.
Step 2: Heat 1 tablespoon of olive oil in a large skillet or Dutch oven over medium-high heat. Brown the meatballs in batches until nicely seared on all sides. They don't need to be cooked through. Remove meatballs from the skillet and set aside.
Step 3: Add the remaining 1 tablespoon of olive oil to the same skillet. Add the diced onion and sliced mushrooms, cooking until softened and lightly browned, about 5-7 minutes. Stir in the minced garlic and cook for another minute until fragrant.
Step 4: Sprinkle the flour over the onion and mushroom mixture. Cook, stirring constantly, for 1-2 minutes to toast the flour.
Step 5: Gradually whisk in the beef broth and Worcestershire sauce, scraping up any browned bits from the bottom of the pan. Bring the sauce to a simmer, stirring until it thickens slightly.
Step 6: Reduce the heat to low. In a small bowl, whisk a ladleful of the hot sauce into the sour cream until smooth. Slowly pour the tempered sour cream mixture back into the skillet, stirring constantly until fully incorporated. Do not boil the sauce after adding sour cream.
Step 7: Return the browned meatballs to the skillet with the sauce. Simmer gently for 10-15 minutes, or until the meatballs are cooked through and heated through, and the sauce is rich and creamy. Taste and adjust seasonings as needed.
Step 8: Serve the Meatball Stroganoff immediately over hot cooked egg noodles, garnished with fresh chopped parsley.