Whisk together the dry ingredients in a mixing bowl.
Cream together the butter and sugar in another mixing bowl, until the mixture is light yellow in color. Add the dry ingredients to the butter/sugar mixture. Beat the eggs in, one at a time.
Fold in the mashed bananas, walnuts, and bourbon.
Pour the mixture into a buttered loaf pan, and bake for 50-60 minutes, until a butter knife or toothpick comes out cleanly.