Preaheat the oven to 350 degrees farenheit. Grease a 9 inch cake pan, set aside.
In a large mixing bowl, cream the butter and sugars together until light and fluffy. Beat in the egg. Stir in the vanilla extract, bourbon and buttermilk until combined. Mix together flour, baking powder and salt. Add flour mixture to creamed mixture. Spread batter into prepared cake pan.
Bake in preheated oven until lightly browned on top, 35 to 40 minutes. Remove cake from oven, and let cake cool completely.