Cream together butter and sugar. Add milk and next three ingredients alternately into creamed butter mixture. Put into ungreased 9 by 9 inch pan.
Mix brown sugar, cocoa, and salt. Sprinkle on top of batter. Do not stir. Pour boiling water over all. Bake at 350 for 40-45 minutes.
Fascinatingly enough, as you pull it out of the oven you will discover that the cake is on top and a thick fudge sauce on the bottom! Serve cold or warm with ice cream, whipped cream, or milk.
Recipe by Amish 365 at https://www.amish365.com/chocolate-fudge-upside-down-cake/