Combine, stir, and heat in a double boiler until smooth:

1/4 c butter

1/2 c brown sugar

1/8 tsp salt

1/3 c cream or evaporated milk

Cool slightly and beat in enough icing sugar (2 c ish) to get the consistency right.

Can also add:

1/2 tsp vanilla or 1 tsp rum

1/2 c chopped nutmeats