Candied Hazelnuts and Chocolate Curls

Preheat the oven to 350F.
Spread the nuts on a baking sheet.
Bake until fragrant and toasted, about 12 minutes.
Transfer to a clean kitchen towel; rub to loosen the skins.
Place the sugar and water in a medium heavy skillet.
Stir with a fork over medium-high heat until dissolved; let boil undisturbed for 3 minutes.
Add the nuts to the pan; stir with a wooden spoon until the caramel seizes around the nuts.
Transfer to a parchment-lined baking sheet; let cool completely.
Once the nuts are cool, place half the chopped chocolate in a deep, medium-size stainless-steel bowl.
Place the bowl over a saucepan with 1 inch of simmering water; stir until the chocolate is melted and hot.
Add the remaining chocolate to the bowl; remove the bowl from the pan of water; let stand about 5 minutes, and then stir until smooth.
Pour half the chocolate onto an inverted baking sheet; spread with a bench scraper until 1/8 inch thick or slightly thinner (chocolate should be opaque on the surface).
Let stand until just tacky.
Hold the scraper at a 45-degree angle; scrape the chocolate off the surface.
The curls can be stored in an airtight container layered with parchment at room temperature.
While the chocolate sets, add the candied nuts to the remaining chocolate in the bowl, and stir until coated.
Spread the nuts on a parchment-lined baking sheet, and let stand until set.
Sift the cocoa powder on top of the dried nuts and toss to coat.
Store in a resealable plastic bag for up to 1 week, until ready to use.