Mix together condensed soups and sour cream in a slow cooker until well combined. Stir in meatballs. Cook on High for 3 to 4 hours.
Fill a large pot with lightly salted water and bring to a boil. Cook egg noodles in boiling water until tender yet firm to the bite, 7 to 9 minutes. Drain.
Toss cooked noodles with butter in a large bowl until well coated. Serve meatballs and sauce over buttered noodles.
