Break up the chocolate and place it in the top of a double boiler over hot water on moderate heat. Stir occasionally until melted and smooth.

Remove the top of the double boiler. Add the condensed milk and stir until smooth, then stir in the raisins.

Use a rounded teaspoonful of the mixture for each cluster, forming 24 clusters and placing them on a piece of aluminum foil.

Let stand at room temperature for about 3 hours until they are firm. Then release each cluster and turn it over to let the bottom dry; they will dry quickly.

Store airtight. Do not let these dry out. They may be frozen. (If you freeze them be sure to let them thaw before unwrapping or they will sweat.)