Special equipment: a piping bag fitted with a round tip
For the cupcakes: Put the beer in a medium saucepan, bring to a simmer and cook until reduced to 3/4 cup, about 30 minutes; allow to cool to room temperature.
Preheat the oven to 350 degrees F. Prepare a 12-cup muffin tin with liners and spray with nonstick cooking spray.
In a large bowl, combine the granulated sugar, flour, baking soda, cinnamon and salt.
In a separate bowl, combine the butter and cooled beer; beat in the eggs, followed by the heavy cream. Add the flour mixture to the wet mixture in 3 parts, stirring to combine between each addition.
Divide the batter evenly among the liners and bake for 12 minutes. Rotate the pan and cook for an additional 12 minutes. The cupcakes should be set in the middle.
For the frosting: In a stand mixer fitted with a paddle attachment, combine the cream cheese, butter and whiskey and beat until combined. Add in the confectioner' sugar a little at a time until the frosting comes together.
Put the frosting in a piping bag fitted with a round tip and pipe in swirls onto the finished cupcakes.