For the egg white doughnuts, beat the egg whites with a pinch of salt in a fat-free bowl until stiff. Briefly mix grated cheese with oat flakes and flour with one third of the beaten egg whites.
Gently fold in the remaining beaten egg whites. Use a spoon to place cookies on a baking tray with baking paper. Bake in a preheated oven (convection oven) at 170 °C for about 20 minutes until brown.