Line a baking sheet with foil and spray the foil with nonstick cooking spray. Combine the sugar, water, and corn syrup in a small saucepan. Stir well until the sugar is moistened.
How to Make Perfect Caramelized Onions
Place the pan over medium heat, and continue to stir as the sugar dissolves. Brush down the sides of the pan with a wet pastry brush to remove any stray sugar crystals.
When the sugar syrup comes to a boil, insert a candy thermometer. Cook the candy without stirring until it is a medium amber color—this should be around 330 F / 165 C. The sugar syrup will be a dark gold color and will start to smell like caramel.
Remove the pan from the heat and stir in the cacao nibs. Once they're coated with the caramel, add the butter and stir it in as well. The butter will help the cacao nibs separate a little bit and will make the mixture easier to spread.
Scrape the candy out onto the prepared baking sheet and spread it into a thin, even layer. Allow it to cool completely at room temperature until cool and hard. Break the candy into small pieces to eat, or chop it up to sprinkle it on top of candies or baked goods. Store in an airtight container at room temperature for up to two weeks.