Toast the hazelnuts in the oven at 180 degrees C (356 degrees F). Spread the nuts in a single layer on a baking sheet and toast until the skins are mostly split and the nuts are light golden brown and fragrant (about 15 minutes).
Remove from the oven and rub the hazelnuts until the loose skins come off.
Let them cool completely and pulse in a food processor until coarsely chopped.
Preheat the oven to 150 degrees C (300 degrees F). Line a baking sheet with parchment paper.
Beat the egg white and salt in a bowl with an electric mixer until stiff peaks form.
Gently fold in the sugar and nuts.
Spoon the batter on the baking sheet with a teaspoon or a tablespoon (it depends on how big you want your cookies) about 4 cm (1.5 inches) apart.
Bake until golden brown, about 30 minutes. Remove and place on a wire rack to cool.
Store the ugly but good cookies in an airtight container for up to 1 week.