Preheat oven to 400 degrees. Line a cupcake pan with cupcake liners and set aside.
In a bowl combine boxed mix with egg, lime zest, ground ginger and butter.
With the help of a mixer (hand or stand) combine all the ingredients until crumbly, it should resemble wet sand.
Mix in vodka. Slowly incorporate ginger beer and buttermilk mixing well until there are no lumps left.
Divide the batter between the cupcake liners and take to the oven. Bake for 15 minutes or until done.
Remove from oven and place on a cooling rack. Cool cupcakes completely before frosting.
Make the Frosting
While the cupcakes are cooling prepare the frosting. Make the basic vanilla buttercream recipe.
Add ground ginger and lime zest and mix well.
Frost the cupcakes and decorate with lime wedges, peppermint and lime zest.
Using silicone cupcake liners means these cupcakes are easy to remove and the liners can be reused.
To make these look even more like a cocktail you can stick a straw out of the frosting! Cut them to size with scissors. It makes a fun garnish.
Make sure the butter is at room temperature before making the buttercream. You'll get the best results that way!
The focus of this recipe should be the ginger since that's really what makes this resemble a Moscow Mule! It may make your frosting an off-white color. It's not coming through in the photos but just know, it won't be a stark white!