1. Finely chop the chocolate and transfer it to a heatproof bowl.
2. Heat the cream until simmering and pour it over the chocolate. Let it sit for one minute and then, using a rubber spatula, stir it from the center outward until smooth.
3. Add the butter and whiskey and stir until combined.
4. Let the ganache cool until thick but still soft enough to be piped.

To fill the cupcakes:

1. Using a 1-inch round cookie cutter (or the bottom of a large decorating tip), cut the centers out of the cooled cupcakes, going about two-thirds of the way down.
2. Transfer the ganache to a piping back with a wide tip and fill the holes in each cupcake to the top.