Cut the butter into small pieces and mix with the chocolate morsels in a microwave-safe bowl. If it has begun to melt, proceed to step 2. If it's still solid, microwave in 30-second increments at low power until the chips begin to met. Do not melt completely!
Heat the cream to a simmer, and pour it over the chocolate-butter mixture. Stir until the chocolate and butter are completely melted.
Warm the Cognac for 10 seconds (trust me, that's enough!) in the microwave. Stir into the chocolate mixture.
Pour the chocolate mixture into a clean pan and chill.
When the chocolate mixture is firm, use a melon baller or a rounded spoon to make balls about an inch in diameter or slightly smaller.
Drop each ball into the cocoa in a bowl, and roll around to coat.