Heat cream, butter and espresso powder in a heavy saucepan stirring often.

Turn off the heat just before it begins to boil and stir with a whisk.

Pour heated mixture over chopped chocolate and let sit for a minute. Then whisk together until the chocolate and cream are combined, melted and smooth.

Pour the chocolate ganache in a small baking pan. Cool to room temperature and then place in the refrigerator to chill for about 30 minutes.

Use a small scoop to form round balls of ganache and place on a wax paper covered baking sheet. Reshape by hand if needed and return to refrigerator to chill for several minutes.

Roll balls in cocoa powder to coat.

Keep refrigerated until serving.