Preheat the oven to 375 degrees F (190 degrees C). Butter a baking sheet.
In a medium bowl, beat the eggs and sugar until thick and smooth. Fold in flour and hazelnuts. Use two spoons to form the dough into balls, and place them 2 inches apart onto the prepared baking sheet.
Bake for 6 to 7 minutes in the preheated oven, or until toasted.