Grease two 9-in. round cake pans and line the bottom with parchment paper; set aside.

In a small saucepan, heat beer and butter until butter is melted. Remove from the heat; whisk in sugar and cocoa until blended.

Combine the eggs, sour cream and vanilla; whisk into beer mixture. Combine flour and baking soda; whisk into beer mixture until smooth.

Pour batter into prepared pans.Bake at 350° for 45-50 minutes or until a toothpick inserted near the center comes out clean. Cool completely in pan on a wire rack.

Meanwhile, make the glaze by heating butter, sugar and whiskey in a small saucepan over low heat. Whisk constantly until butter melts and sugar dissolves.

Carefully slice each layer of cake horizontally to create 4 cake layers.

Brush each layer generously with whiskey glaze. Allow to absorb for at least 20 minutes.

Meanwhile make the frosting by beating together butter, 4 cups powdered sugar, Bailey's Irish Cream and vanilla extract in large mixing bowl until well combined. Add additional powdered sugar 1/2 cup at a time until desired consistency is achieved.

Spread one cake layer with frosting. Stack another layer on top and repeat until all layers are stacked. Spread the top and sides of the cake with frosting.

Slice and enjoy!