Free-form hazelnut florentines

Instructions

1. Arrange an oven rack in the center position and preheat the oven to 180°C.
2. Spread the hazelnuts on a baking tray and toast until they're golden brown and fragrant, 8 to 10 minutes, tossing halfway through. Let the nuts cool on the pan, then transfer to a cutting board and chop very finely until the largest pieces are no bigger than a lentil (some of the nuts will turn to dust, which is okay). Transfer the chopped hazelnuts to a small bowl and set aside. Leave the oven on.
3. In a small saucepan, combine the butter, sugar, cream, and honey and bring to a boil over medium-high heat, stirring constantly with a heatproof flexible spatula to melt the butter and dissolve the sugar. Once the mixture is at a full, rolling boil, remove the saucepan from the heat and vigorously whisk in the flour and salt until the mixture is smooth and lump-free, then add the vanilla and hazelnuts and stir until combined. Scrape the batter into a medium bowl and set aside.
4. Line a large baking tray with baking paper, then cut a second piece of paper to the same size. Scrape about half of the warm batter onto the paper-lined tray, then place the second piece of paper on top. Working over the second piece of paper, use a small offset spatula to spread the batter into as thin a layer as possible between the two sheets, pressing down firmly and pushing the mixture outward toward the margins (the overall shape isn't important). Transfer the sheet pan to the refrigerator and chill until the batter is firm and set, 8 to 10 minutes.
5. Remove the baking tray from the refrigerator and carefully peel away the top piece of paper, leaving the layer of batter on the baking tray. Bake until the batter has transformed into a lacy, web-like slab that's golden brown across the surface, 8 to 10 minutes, rotating the tray front to back after 6 minutes. Remove the baking tray from the oven and let it cool completely.
6. Break the cooled slab into large fragments on the baking tray, then transfer the pieces to a wire rack. Repeat the spreading, chilling, and baking process with the remaining batter using the same tray and paper (the remaining batter will have cooled and firmed up, so you'll need to press even more firmly with the spatula to spread it). When the second slab of florentines is cool, break it into pieces and transfer them to the rack. Reserve the empty lined tray.
7. Fill a small saucepan with about 2.5 cm water and bring to a simmer over medium heat, then reduce the heat to maintain a gentle simmer. In a medium heatproof bowl, combine the unsweetened chocolate and chocolate hazelnut spread and set it over the saucepan, taking care that the bottom of the bowl doesn't touch the water (this is called a double boiler). Stir the mixture occasionally with a heatproof flexible spatula until it's melted and completely smooth, then remove the bowl from the heat and set aside. Let the chocolate mixture cool, stirring occasionally, until it's thickened.
8. Use a small offset spatula to spread a very thin layer of the chocolate mixture across the flat bottoms of the florentines, then set the coated florentines chocolate-side down on the reserved baking tray (when you run out of room, line another tray with baking paper and place the remaining florentines on it). When all the pieces are coated, transfer the trays to the refrigerator and chill until the chocolate mixture is set, 10 to 15 minutes.