In a large skillet or Dutch oven, heat the olive oil over medium heat. Add the diced onion and sliced mushrooms. Sauté until the onions become translucent and the mushrooms are softened, about 5-7 minutes.
Add the ground beef to the pan, breaking it apart with a wooden spoon. Cook until browned, about 5 minutes. Drain any excess grease if necessary, but leave some for flavor.
Stir in the garlic powder, Worcestershire sauce, salt, and pepper. Mix well, allowing the spices to coat the beef and vegetables.
Pour in the beef broth and water. Sprinkle the brown gravy mix over the mixture and stir until everything is well combined. Bring to a gentle simmer.
Add the egg noodles to the pot, ensuring they are submerged in the liquid. Cover the skillet and cook according to the noodle package instructions, typically about 8-10 minutes, stirring occasionally.
Once the noodles are cooked and the liquid has reduced, stir in the cream of mushroom soup until fully combined. This is where the magic happens!
Remove the pot from heat and gently fold in the sour cream. This will give your Ground Beef Stroganoff(One Pot!) that signature creamy texture.
Taste and adjust seasoning if necessary. Serve hot, garnished with parsley or additional mushrooms if desired.