Prep your cake pan by spraying liberally with non-stick baking spray, then a light dusting with cocoa powder. Set to the side. Make ganache = In a medium saucepan heat your cream to a light bubble. Place your chocolate in a double boiler.Pour heated cream over chocolate pieces and let sit for 1 minute, then stir to combine. Make sure to stir often until chocolate melts. Stir in Whiskey if using, and salt to taste.Set ganache aside to cool to room temperature.
In a medium saucepan add the stout, coffee, and butter. Heat over medium, stirring often until butter melts. Add in the cocoa powder and mix until smooth. Set the mixture to the side and allow to cool to room temperature.
In a medium bowl, whisk flour, sugar, baking soda, and salt.In a stand mixer, add your eggs and sour cream. Beat on medium until combined.Reduce the speed to low and add the chocolate beer mixture.
Mix until well combined. Begin to add flour mixture in thirds. Beat on low until combined. Pour the batter into your springform pan.
Place a trivet in your Instant Pot. Add 3/4 cup water to the Instant Pot. Lower the cake into the Instant Pot on the trivet. Seal and cook on high pressure for 35 minutes, then vent immediately.
Let the cake cool. Place the ganache you made in the microwave for 45 seconds, heat until melted. Pour the ganache over the top of the cake. Set to the side.
Prepare your frosting = Add softened sticks of butter to the mixer. Add Baileys Irish Cream Liqueur. Mix until butter and liqueur are completely blended. Add powdered sugar. Beat on low until well combined and stiff peaks begin to form.
Then move the mixer up to medium-high speed.Blend for 1 minute. Spread the frosting on top of the cake.Enjoy!