Bring a large pot of water to a boil. Add egg noodles, and cook according to package directions. Drain and set aside.
While noodles cook, brown ground beef in a large skillet over medium-high heat until all the pink is gone. Drain any fat; set aside.
In the same pot you cooked the noodles in, combine the sour cream, cream of mushroom soup, and onion powder over medium heat. Cook for 2 to 3 minutes until warmed through. Add noodles and ground beef. Stir until well combined. Season with salt and pepper to taste.