Preheat the oven to 350°F(175°C). Fill a cupcake pan with cupcake liners and set it aside.

Mix the flour, cocoa powder, salt and baking soda together in a bowl.

In a stand mixer (or with a hand mixer), cream together the butter and sugar until light and fluffy, about 3 minutes.

Add eggs, one at a time, while mixing, then add sour cream. Beat until well blended.

While still mixing, pour in half the dry ingredients then half the stout, then vanilla extract, then remaining dry ingredients, then remaining stout. Mix just until combined, do not over blend.

Fill the cupcake liners with the batter to 3/4 full. Bake for 17-19 minutes, until a toothpick inserted in the center comes out clean.

Remove from the oven and cool completely on a cooling rack.

Once the cupcakes are cool, use a knife or apple corer to remove a small chunk of cake from the center.

Place the chocolate in a heatproof bowl.

In a saucepan, heat the whipping cream until steaming, but not bubbling (do not boil).

Pour the hot cream over the chocolate and let it sit for 10 minutes. Stir with a rubber spatula until the chocolate chips are melted and the ganache is smooth. Cool completely.

If the ganache is very thin, you can thicken it by adding a tablespoon or two of powdered sugar (only if necessary).

Fill the centers of the cupcakes with ganache either by spooning it in or using a piping bag.

In a mixing bowl, whip the butter until smooth and fluffy, about 5 minutes.

Gradually add the powdered sugar until fully incorporated.

Pour in the Irish Cream and whip for another 2-3 minutes until light and fluffy.

Pipe the frosting onto cupcakes with a piping bag and large decorator tip.

Decorate with sprinkles, if desired.