Combine the heavy cream, butter, baking chocolate, chocolate chips, and espresso powder in a saucepan over medium heat; stirring constantly, cook until the chocolate has melted into a smooth and thick mixture. Remove from heat. Pour into a bowl and chill in refrigerator until the mixture hardens, about 1 hour
Line a baking sheet with waxed paper. Scoop small balls of the chocolate mixture onto the waxed paper. Store in refrigerator until the balls harden completely. Store in a cool, dry place.