Grind the almonds and hazelnuts to a fine consistency. Mix in the flour.
Whip the egg whites until they are foamy and doubled in volume. Gradually add the sugar and whip to stiff peaks. Carefully fold in the ground nut mixture by hand.
Divide the batter equally between 2 half-sheets of baking paper (12 × 16 inches/30 × 40 cm). Using a spatula, spread