Preheat oven to 325°F Grease and flour a standard tube pan.

Cook sweet potato in boiling water until tender; or, for richer flavor, bake in the oven. Cool, peel and mash until you have 1 cup puree.

Cream butter together with sugars in a large mixing bowl. Mix in sweet potato puree. Add eggs, 1 at a time, beating well after each addition.

Sift flour, baking powder and salt together and add alternately with milk. Pour into pan and bake 60 to 70 minutes.

While cake is baking, make Irish Whiskey Glaze:

Combine whiskey, sugar and butter in a small saucepan. Bring to a boil to dissolve sugar.

When cake tests done remove to a rack. Pour a portion of glaze over hot cake in pan. Let soak in a little before adding all the glaze. Cool completely in pan and gently remove to a plate.