Nothing screams retro like gravy.
Here is a learned at Mama’s knee recipe for Mushroom Gravy:

1 can mushroom soup

1 can sliced mushrooms (drained)

1 envelope onion soup mix

1 cup of water or milk
Mix together in saucepot. Bring to boil. Reduce to simmer. Simmer 10 minutes, adding a bit of flour or cornstarch if it needs thickening.