01 - Line an 8x8-inch square baking pan with parchment paper, leaving an overhang on two sides for easy removal.
02 - In a large mixing bowl, toss together the chopped hazelnuts, shredded coconut, and crisped rice cereal until evenly distributed.
03 - In a small saucepan over low heat, melt the coconut oil. Stir in the maple syrup and fine sea salt until fully blended.
04 - Pour the warm liquid over the dry ingredients and fold thoroughly until every piece is evenly coated and sticky.
05 - Transfer the mixture to the prepared pan and press firmly into an even, compact layer using the back of a spoon or a flat-bottomed glass.
06 - Place the pan in the freezer for 15 minutes to allow the base to firm up.
07 - Set a heatproof bowl over a pan of gently simmering water and melt the dark chocolate with the coconut oil, stirring frequently until completely smooth. Alternatively, microwave in 20-second bursts, stirring between each interval.
08 - Remove the base from the freezer and pour the melted chocolate over it, spreading evenly with a spatula to cover the entire surface.
09 - Scatter toasted coconut flakes and chopped hazelnuts over the wet chocolate, then finish with a light pinch of flaky sea salt.
10 - Refrigerate for at least 30 minutes, or until the chocolate topping is completely set and firm to the touch.
11 - Lift the slab out of the pan using the parchment overhang, transfer to a cutting board, and slice into 16 even bars with a sharp knife.
12 - Keep bars in an airtight container in the refrigerator for up to one week.