From The Violet Bakery Cookbook by Claire Ptak: "We use these shards in our Butterscotch Blondies, but you could add them to almost any cake, cookie, or bar and, of course, they would be awesome in brownies. Any leftovers can be kept in a plastic container in the freezer for up to three months."
Have a sheet of parchment paper ready on a heatproof surface. Measure the 2 tablespoons of water into a heavy-bottomed pot. Cover with the sugar and place over medium-low heat until the sugar starts to dissolve. Resist the temptation to stir the pan, as this can cause crystallization. Once the sugar starts to dissolve, turn up the heat to medium-high until the sugar is dark golden brown.
Pour the caramel onto the parchment paper in a thin and even layer. Leave to cool, then use a sharp knife to chop into smallish shards. Be careful, as the caramel can be quite hard.
Use right away or store in a plastic bag or sealed container in the freezer. Do not store it in the fridge or it will soften, melt together, and become tacky.