Thanks to Darryn Ray Brott for the YouTube
Rump Steak Serenade was recorded July 1, 1941 in Hollywood. Fats Waller did the vocal and piano with a studio pickup orchestra including vocalists. He wrote the song and lyrics, but for Fats that probably took no more than 15 minutes. Clearly a swing era sound and feel, and no mistaking the Fats Waller touch. He was amazing.