1 pound butter, softened 
1 pound brown sugar 
1 pound powdered sugar 
2 teaspoon cinnamon 
1-1/2 teaspoon nutmeg 
dash all spice 
1.5  quarts vanilla ice cream, softened 

Cream butter and add sugars to mix well.  Add the spices and mix well again. Add the ice cream and guess what - mix well for the last time.  Once mixed put into individual containers and put into the freezer. Will stay for a long time. 

When you get ready to use just add a heaping tablespoon of the hot
butter rum mix (a little more is better than a little less) with rum (as much as you like) and about 8-10 ounces of hot water.  Mix well and drink up. 

Enjoy