Melt the chocolate and butter in a heavy bottom saucepan or over a double boiler.

Mix the Kahlua into the chocolate mixture. Beat until smooth.

Transfer chocolate-Kahlua mixture to refrigerator to set to semi-soft solid. (NOTE: It should not stick to your hand when you handle it.)

Pour cocoa powder onto a plate.

Using a melon baller, scoop out chocolate-Kahlua mixture and drop onto the plate of cocoa powder.

Roll the truffle in the cocoa powder until the outside is entirely coated.  Place completed truffles on clean plate. Repeat with remaining chocolate-Kahlua mixture.

Transfer to refrigerator to set for 15 minutes.

Store in a sealed container at room temperature.