Place the butter on a small plate, and let it soften at room temperature.
Put the softened butter, powdered sugar and milk in the bowl of a stand mixer. Use the bowl shield. Turn the mixer on low speed and cream the butter and sugar.
As you continue to blend the butter and sugar mixture, add milk a few drops at a time to achieve a consistency a bit thinner than modeling dough. Test it by rolling a tablespoon or so of the mixture into a ball to see if it holds its shape.
Using a tablespoon or small melon baller, roll balls about 1 inch in diameter. Place the balls on a parchment-lined cookie sheet and put in the freezer until frozen.
Melt dark or milk chocolate in a double boiler.
Use a toothpick or small skewer to dip each frozen cream ball into the melted chocolate.
Let the chocolates harden a little, then roll each in cocoa powder, cinnamon and sugar, powdered sugar, finely ground nuts or colored sprinkles.
Place the chocolate-covered balls on the parchment to finish setting. Speed the process up by setting the cookie sheets in the refrigerator for a few minutes.
Store the chocolates in an airtight container in a cool place. Keep away from heat or sunlight.
Add flavorings to the cream after the first addition of the milk. Add only 1 to 2 drops so as not to overpower the cream filling or thin it out too much. Use vanilla, peppermint, almond or orange flavorings. Experiment with your favorites.