Melt the butter and the chocolate over a bain-marie. Carefully stir in the icing sugar, almonds, mascarpone and the liqueur. Remove from the heat and leave to set. Knead into oval balls and press them onto the countertop so that they stay put. Top with a whole almond. Melt the milk chocolate over a bain-marie and dip half the chocolates into it. Leave to dry on a rack or on baking paper.