1 1/2 sticks melted butter
1/2 cup unsweetened cocoa powder
1 can sweetened condensed milk
1 tsp vanilla
Sift cocoa into mixing bowl, mix in melted butter
on medium high speed until smooth.
Add sweetened condensed milk and continue to mix until smooth.
Add vanilla and mix until smooth.
Spread frosting on cooled cake, let stand 2 hours to set.