Hot Buttered Rum Mix for a Crowd

1 lb. brown sugar
1 lb. powdered sugar
1 lb. butter
1 qt. vanilla ice cream
1 t allspice
1 t cinnamon
1 t nutmeg
rum

Mix all ingredients except rum. Heat very slowly until mixture is like thin cake batter. Remove from heat; cool. Cover and freeze. When ready to serve, put 2 teaspoons frozen mixture in a mug, add 1 1/2 oz of rum. Fill remainder of cup with hot water and stir to melt frozen mixture. Sprinkle with nutmeg.