Put chocolate pieces in a medium bowl. Set aside.
Combine the cream and the coffee in a small saucepan.
Bring to a boil; remove from heat, cover, and steep for 5 minutes.
Strain milk mixture and pour back into saucepan.
Add corn syrup and return to a boil.
Remove from heat.
Pour milk mixture over chocolate.
Stir gently until chocolate has melted.
Stir in butter.
Drizzle in coffee liqueur. Stir to combine.
Pour chocolate mixture into a clean glass bowl or small glass casserole.
Place a piece of plastic wrap over the surface of the chocolate mixture.
Refrigerate for at least 30 minutes, or until firm.
While mixture is chilling, line a sheet pan with parchment paper.
Remove chocolate mixture from refrigerator and portion filling using a small cookie scoop.
Place on prepared baking sheet.
Refrigerate again for 30 minutes.
While waiting for the chocolate mixture, sift ½ cup cocoa powder on a plate.
Remove chocolate from refrigerator.
Coat hands with cocoa powder and roll each scoop of chocolate into a ball.
Place back on baking sheet and return to refrigerator for another 30 minutes.