Serves: 30 mini cupcakes
Preheat the oven to 375°F and line 30 mini muffin tin cups with paper liners.
Beat the butter and sugar together until light in colour. Beat in the egg and vanilla, and then beat in the mashed potatoes and milk.
In a separate bowl, sift the flour, baking powder and salt. Add this to the butter mixture and stir until evenly combined. Pipe or spoon this into the prepared muffin cups, only filling each halfway with batter. Bake the cupcakes for about 12 minutes, until a tester inserted in the centre of a cupcake comes out clean. Cool the cupcakes in their tin before glazing.
For the glaze, heat the cream and butter to just below a simmer and pour this over the chocolate, letting it site one minute before whisking until smooth.
Carefully pour this over the cupcake, to fill up to the top of the paper liner and chill the cupcakes about an hour to set the glaze. Add desired garnish before serving.
The mini cupcakes will keep, refrigerated, for up to 3 days.