Double Chocolate Stout Cupcakes With Irish Cream Buttercream Frosting

For the cupcakes:
Preheat oven to 350u0b0F. Line muffin cups with paper liners.
Combine flour, granulated sugar, salt and baking soda in a bowl and set aside. Cream together sour cream and eggs in a mixing bowl until well blended.
Over medium heat, heat the beer and butter until simmering. Add the cocoa powder and whisk until smooth. By smooth, I mean no large lumps. It will never look entirely smooth. Remove from heat.
Add cocoa, beer, butter mixture to the egg mixture and beat until just combined well.
Next add the flour mixture and beat until just combined. Remove the bowl from the mixer and use a spatula to ensure all ingredients are incorporated, scraping the sides and bottom of the bowl.
Fill muffin cups 2/3 to 3/4 full (depending on your preference). Bake for 15-17 minutes or until a toothpick inserted in the center comes out clean. Remove from the oven, allow to cool for 10 minutes and transfer cupcakes to a wire cooling rack. Cool completely before frosting.
For the frosting:
Cream butter in a mixing bowl until light and fluffy. Add 2 cups of sugar slowly, beating well to incorporate. Add the Irish Cream and continue mixing. Continue adding remaining sugar and beating. Add 1 to 2 tablespoons light cream or milk for smoothness. Frost cooled cupcakes.