Preheat the oven to 325F and grease a 24-cup mini muffin tin.
Beat the butter and sugar together until well-combined, then beat in the egg. Stir the sour cream, espresso and vanilla together and add this to the butter mixture, blending well.
In a separate bowl, sift the flour, baking powder, baking soda, salt and cinnamon together. Add this to the butter mixture and stir just until blended. Spoon or pipe this into the prepared mini muffin tin and bake for about 18 minutes, until a tester inserted in the centre of a mini cake comes out clean. Cool the cakes in the tin before turning out.
To assemble, break or cut the pretzel twists so that the large curls can be stick into the side of each mini cake to replicate the handle of an espresso cup. Pipe or dollop a little whipped cream on top of each mini cake and sprinkle with some grated chocolate. Chill to cupcakes up to 4 hours before serving.
The cakes can be stored, undecorated, in an airtight container for up to 4 days, or for 4 to 6 hours refrigerated, once topped.