Coffee candy is built on a basic caramel base with fat and cream added for chewiness and espresso powder to give it a coffee kick. Determine its hardness by adjusting the ratio of heavy cream to sugar: 2 parts granulated sugar to 1 part heavy cream produces a soft, chewy candy, while 2 parts granulated sugar to 1/2 part heavy cream produces a hard, but still pliable, candy. Keep a bowl of ice water close when working with sugar. Boiling sugar burns longer and hotter than water, and ice water can literally save your skin if you get splattered.
Line a baking dish with an oversized piece of parchment paper or aluminum foil. Spray the liner with cooking spray. You need a 13-by-9-inch pan to make one batch of candy.
Mix 2 parts granulated sugar, 1 part each firmly packed brown sugar, light corn syrup, heavy cream, milk and butter, 1/4 part espresso powder and a pinch of salt in a heavy-bottomed saucepan. You need 2 cups of granulated sugar to make one batch of coffee candy, or about 70 1 1/2-by-2-inch pieces when poured in a 13-by-9-inch pan.
Attach a candy thermometer to the pan and cook the candy mixture over medium heat until it boils, about 15 to 20 minutes. Stir occasionally while the candy mixture melts.
Cook the candy until it reaches 250 degrees Fahrenheit. Remove the saucepan from the heat and stir in secondary flavoring ingredients, such as a teaspoon of vanilla, orange or cinnamon extract. Secondary flavorings are optional.
Pour the coffee candy in the pan and let it cool to room temperature. Pull the candy out of the pan and slice it into pieces using a pastry wheel or chef's knife. If the wheel or knife stick, spray the blade with cooking spray.
Wrap each candy in wax paper and store at room temperature for up to 2 weeks.