Preheat the oven to 160℃ fan / 180℃ / 356℉.
Line 3 trays with baking paper.
Beat the eggs and sugar together in a large bowl with a balloon whisk until light and fluffy.
Add the hazelnut meal, ground cinnamon and salt and stir in until well combined.
Sprinkle the ⅛c sugar onto a plate.
Take teaspoons of the cookie dough and roll into balls.
Lightly roll the balls in the sugar to coat, then place on the lined baking trays, leaving room inbetween each cookie.
Flatten each cookie slightly with clean fingers, then top with a hazelnut, pressing it into the dough slightly.
Bake in the preheated oven for 14-15 minutes, until the edges are a very pale golden, and the cookie looks matte rather than shiny.
(You may need to cook them in two batches, depending on the size of your oven.)
Leave the cookies on the trays for 5 minutes, then move to a wire rack to cool completely.
Store in an airtight container at room temperature for up to a week.