Put the cream, honey, and instant espresso powder into a small saucepan and bring to boil. Remove from the heat and pour over the chopped dark chocolate and diced butter in 2-3 additions, stirring well after each addition. Let cool. Cover with plastic wrap and leave to set overnight at room temperature.
The next day, transfer the ganache to a piping bag fitted with a tip of your choice and pipe 2 swirls on top of each cupcake. Decorate with pretty sprinkles and serve.