1 lb. confectioners' sugar
3/4 c. cocoa
1 stick butter
1/2 c. nuts (optional)
1 tsp. vanilla
1/4 c. milk

Ann has modified the original directions to match the speed of cooking with a microwave.

Melt butter on High in a bowl. Put all the other in the bowl. Blend with the mixer until smooth. Put in pan. Refrigerate at least 1 hour. Enjoy!

The original directions: Sift sugar and cocoa into 9 inch square ungreased microwave safe dish. Cut butter into 5 pieces and place on top of sugar mixture. Pour on milk. Do not stir. Nuke uncovered 2-3 minutes on High until bubbly. Remove and stir until smooth. Add nuts and vanilla. Refrigerate 1 hour to set.