Line a small baking tray or plate with parchment paper and keep it nearby for later.

Place the chocolate into a medium bowl and melt it gently in the microwave, stirring every so often until smooth and glossy. Stir in the hazelnut butter, or almond butter if you prefer, until the mixture is rich and creamy. Add the crushed waffle cone and a small pinch of sea salt, then mix everything together well. Cover the bowl tightly and chill in the refrigerator for about 30 minutes, just until the mixture is firm enough to shape but still soft to the touch.

Once chilled, scoop out about 12 portions using a melon scoop or tablespoon. Roll each piece between your palms to form neat little balls. Press a whole hazelnut into the center of each one, then close the mixture around it and roll smooth again. If the mixture begins to soften too much while working, place it back in the refrigerator or freezer for a few minutes to firm up. Arrange the truffles on the prepared tray and chill again while you make the coating.

For the coating, melt the milk chocolate in a clean bowl until silky smooth. Stir in the grapeseed oil to loosen the chocolate and give it a beautiful shine, then mix in the chopped hazelnuts.

Using a fork, lower each cold truffle into the melted chocolate, turning gently so it is fully coated. Lift it out carefully and let the excess chocolate drip away before placing it on a cooling rack set over parchment paper. Leave the truffles until the coating begins to set and harden.

Transfer the finished truffles to a serving plate or airtight container and keep them chilled in the refrigerator until ready to serve.