3/4cup1 1/2 sticks unsalted butter, room temperature
2 to 3tablespoonsginger beer
Juice of half a lime
1 to 2teaspoonsground gingerdepending on how ginger-y you like the cupcakes
Preheat the oven to 350° F. Line a cupcake pan with cupcake liners. Set aside.
Heat the butter, ginger beer and rum over low heat for about 3 minutes, until the butter melts, being careful not to boil. Set aside to slightly cool.
In a small bowl, beat together the egg and buttermilk. Set aside.
In a medium bowl, whisk together the cocoa powder, cinnamon, ginger, flour, sugar, salt, baking soda and baking powder.
Stir the warm butter mixture into the dry ingredients. Add the egg mixture and stir until well combined.
Fill cupcake tins three-quarters full and bake for 16 to 20 minutes, or until a toothpick inserted into the center of a cupcake comes out clean. Cool on a wire rack for 5 minutes, or until cool enough to handle. Remove the cupcakes from the pan and cool completely.
For the frosting, use an electric mixer and beat butter until whipped. Slowly add confectioners' sugar followed by the rum, ginger beer, lime juice and ground ginger (to taste). Transfer to a frosting bag and frost the cupcakes. Garnish with candied ginger.