Thoroughly combine flour, sugar, cocoa powder, baking soda and salt in mixing bowl.
Add butter and mix using an electric mixer until mixture is crumbly
Add eggs and ½ of the stout beer, mix until a paste forms.
Add the remaining ingredients and mix until combined.
Divide cake batter between two 9” round prepared cake pans.
Bake at 350˚ for 25-35 minutes or until the top of cake “bounces back” when lightly pressed.
Beat butter with an electric mixer on low until very smooth.
Add shortening and continue to mix, occasionally scraping down sides of bowl, until very smooth
Add half of powdered sugar and mix on low speed until smooth, occasionally scraping down sides of bowl
Add half of the Irish cream whiskey, mix until smooth
Add remaining Irish cream whiskey, heavy cream and salt. Mix until smooth.
Place all ingredients in a heavy bottom sauce pan over very low heat.
Stir until melted.