Melt cocoa butter in a small saucepan over low heat; set aside to cool. Heat chocolate in a heatproof bowl set over a pan of simmering water until it reaches 110 degrees to 115 degrees on a candy thermometer.Advertisement
Heat corn syrup in small heavy-bottom saucepan over low heat until 95 degrees, and pour into melted chocolate. Stir in cocoa butter. Set aside in a cool, dry place, stirring occasionally until mixture is firm and pliable, 1 1/2 to 2 hours.
Wrap mixture tightly in plastic. Press into a disk, and let stand at room temperature 8 hours or overnight.
On a surface lightly dusted with cocoa powder, knead dough until smooth. Wrap tightly in plastic, and store at room temperature up to 1 month.