Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9×13 inch pan.
In a large bowl, stir together cake mix and pudding mix. Make a well in the center and pour in eggs, milk, whiskey and butter. Beat on low speed until blended. Scrape bowl, and beat 4 minutes on medium speed. Reserve a 1/4 cup each of the butterscotch chips and walnuts for the top of the cake. Stir in the remaining butterscotch chips and walnuts to the batter. Pour batter into prepared pan and sprinkle with reserved chips and nuts.
Pour batter into prepared pan. Bake in the preheated oven for 50 to 60 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow to cool.