Use this recipe to make Blum's Coffee Crunch Cake.
Line a rimmed baking sheet with a nonstick cooking mat; set aside.
In a small saucepan, combine the sugar, coffee, and corn syrup. Bring to a boil. Cook over medium heat to 300 degrees on a candy thermometer.
Remove from heat for 10 seconds. Sift baking soda evenly over sugar syrup. Whisk just until combined. Pour immediately into the center of the prepared baking sheet. Let stand, without spreading, until cool, about 30 minutes.
When ready to use, tap the crunch lightly with a spoon or knife handle to crack. Break into irregular pieces.