In a mixing bowl, stir together the hazelnut butter, honey, and vanilla extract until smooth.

Add the puffed buckwheat and mix until fully coated.

Line a loaf pan or glass container with parchment paper and transfer the mixture into it. Press it down firmly using the bottom of a glass or a spatula. I used two containers for this recipe.

In a double boiler, melt the dark chocolate. If using, stir in the extra hazelnut butter for a creamier finish.

Pour the melted chocolate over the packed buckwheat mixture and spread it evenly.

Sprinkle sea salt on top.

Freeze for about 2 hours or until the chocolate is firm.

Remove from the freezer, cut into bars, and store in the fridge.