1 cup granulated sugar
1/4 cup water
2 tablespoons espresso beans, crushed with a rolling pin or
    chopped in a food processor to medium-fine crumbs
2 tablespoons butter
Pinch salt

Line a baking sheet with kitchen parchment and spray the parchment with nonstick cooking spray or grease it lightly.

In a medium heavy-based saucepan, combine the sugar and water. Heat over high heat, swirling the pot occasionally (don't stir it) for even color, until it turns light amber. Add the crushed espresso beans (don't worry if the sugar seems to foam), swirl them around in the caramel, and continue to cook until the caramel turns brown. Remove the pan from the heat. Carefully whisk in the butter and salt (the butter will sputter). Immediately pour the brittle onto the prepared baking sheet, quickly tilting the baking sheet to get the brittle to flow into a thin layer (be careful - the brittle is very hot). As it cools and slows down, use a metal spatula to spread it into an even thinner layer. Let cool. Chop two-thirds of the cooled brittle into small pieces by sealing it in a plastic bag and smashing it with a mallet or rolling pin. Sift the crumbs in a strainer if you don't want the powder. Break the remaining brittle into shards and use them to garnish bowls of the ice cream.

NOTES:
When you add the crushed coffee beans to hot caramel, the caramel will foam and spurt. Just keep swirling the pan until the caramel turns brown.

Tilting the baking sheet while the brittle is hot encourages it to spread. Use a metal spatula to spread it even thinner for a more delicate crunch.