Preheat the oven to 180°C (356°F).
Whip the egg whites thoroughly with a whisk until foamy.
Add the sugar in 2-3 portions while continuously mixing.
Sift cake flour and almond powder together, then add to the egg white mixture and combine.
Finely chop walnuts or other nuts and add to the batter.
Shape the batter into streusel mounds on a baking tray.
Bake in the oven at 180°C (356°F) for about 20 minutes.