Bring a large pot of lightly salted water to a boil. Add egg noodles and cook for 8 to 10 minutes; drain.
In a skillet over medium heat, brown the ground beef with onion until done; drain away excess grease.
Mix mushroom gravy powder, cubed cream cheese and undrained mushrooms with ground beef until thoroughly blended and cream cheese has melted. Add milk, sour cream, and mushroom soup to the mixture and blend well.
Combine Pasta with Hamburger mixture and blend well. Serve.