The oven is preheated to 180C degrees. Prepare paper trays cakes (about 10-12 depending on their size) in the tray. It is recommended that the butter is at room temperature. For the cupcakes: Mix the butter with the sugar, then add the flour, salt, egg and 3-4 tbsp of the dissolved coffee. The mixture must be thick, but the liquid; can be dosed with a spoon. Distributed in paper shapes and bake about 20 minutes. For decorative mixture: The butter mix with a mixer or wooden spoon until it becomes creamy appearance. To this was added the sieved powdered sugar and stir until a light, fluffy cream. Last added coffee until the mixture looked like a cream spreads (careful not to get too liquid, it is possible to stay from the dissolved coffee in excess). Poured into a syringe and cooled cupcakes decorated to your taste and desire.