Step 1

Fill a large pot with lightly salted water and bring to a rapid boil. Cook egg noodles at a boil until tender yet firm to the bite, 7 to 9 minutes; drain.

Step 2

Meanwhile, melt butter in a large skillet over medium-high heat. Sauté onion in hot butter until tender and translucent, about 5 minutes. Add ground beef in small chunks; cook and stir beef until browned and crumbly, 5 to 7 minutes.

Step 3

Sprinkle flour over beef mixture; cook and stir for 1 minute. Stir in mushrooms and garlic salt. Pour in mushroom soup and chicken soup; cook and stir until heated through, about 5 minutes. Stir in sour cream until smooth and heated through, 2 to 3 minutes more. Serve beef mixture over cooked egg noodles.