Preheat the oven to 350°F (175°C) and line a cupcake tin with liners.

In a saucepan, bring the Guinness to a simmer over medium heat. Stir in cocoa powder until smooth. Remove from heat and let cool.

In a bowl, whisk together flour, baking soda, and salt.

In another large bowl, beat together the butter, sugar, and brown sugar until light and fluffy. Add eggs, one at a time, mixing well after each. Stir in the vanilla.

Gradually add the cooled Guinness mixture to the butter/sugar mixture.

Slowly add the dry ingredients to the wet ingredients, mixing until just combined.

Divide the batter into the cupcake liners, filling each about 2/3 full.

Bake for 18-20 minutes or until a toothpick comes out clean. Let cool completely.

For the frosting, whip the heavy cream until soft peaks form, then slowly add powdered sugar and sea salt.

Frost the cooled cupcakes with the salted caramel buttercream and enjoy!