1) Prepare the ingredients. Chop the milk and dark chocolate. Pour the cream in a saucepan, add the instant coffee and the butter, slowly bring the mixture to a boil, then remove the pan from the heat. add the chopped chocolate, let it rest for 2-3 minutes, then mix, so as to melt and mix the chocolate completely.
2) Do it cool down. Pour the cream into a bowl and put it to cool for about 1 hour in the refrigerator, stirring the mixture from time to time.
3) Form truffles. Take the mixture from the fridge and, with a teaspoon, form many irregular balls the size of a walnut. Arrange them, as you prepare them, on a tray lined with a sheet of baking paper, then put them on in the fridge to cool for 30 minutes. Pour the cocoa powder into a large bowl or baking dish, then dip the prepared truffles and rotate them to cover them completely. can serve them immediately, or store them in the refrigerator, in tin boxes. If you like, you can replace the instant coffee with 1 tablespoon of rum, to offer truffles at the end of the meal with a selection of sweet wines and liqueurs.