Preheat oven to 350 degrees. In a pie plate or baking sheet, toast the hazelnuts until the skins blister, about 15 minutes. Transfer the nuts to a clean kitchen towel and let cool, then rub to remove the skins. If you don’t mind hazelnut skins, you can skip this step. Coarsely shop the nuts and set aside.

Melt the chocolate in a heatproof bowl set over a pan of simmering water until smooth.

Meanwhile, line a sheet pan with parchment paper. Using a ruler and a pencil, draw a 9-by-10-inch rectangle on the paper. Turn the paper face-down on the baking sheet.

Once the chocolate is melted, place half the dates and half the chopped hazelnuts into the bowl with the chocolate and stir to combine.

Pour the chocolate mixture onto the parchment, into the middle of rectangle you drew, and spread out to the edges of the rectangle using a spatula.

Sprinkle the remaining hazelnuts and dates evenly over the chocolate, followed by the sea salt.

Let sit at room temperature for at least 2 hours, or in the fridge for 1 hour to harden, then chop into desired shapes.

Serve at room temperature and store in tightly sealed container for up to a week.