Preheat the oven to 180°C (fan oven) and line a 12 hole cupcake tray with cases.
In a small bowl mix the freshly ground coffee or espresso powder with the water. Set aside for now.
Beat the butter and sugar together in a large mixing bowl until creamy and pale in colour.
Beat in the eggs, one by one, adding 2 tablespoons of the 180g self-raising flour at the same time (this will stop the mixture from curdling).
Now add the remaining self-raising flour, and the coffee mixture, and fold together until fully combined.
Divide evenly between the cupcake cases, filling them roughly ¾ full.
Bake for 16-18 minutes, until the cupcakes have risen and a toothpick inserted into the middle comes out clean. Leave to cool on a wire rack.