Finely chop the biscuits. Beat the egg white with the whisk of the hand mixer until stiff, adding salt and sugar. Fold in the cookie crumbs. Line 1-2 baking trays with baking paper. Use a teaspoon to place approx. 25 blobs on the baking paper. Dry in a preheated oven (electric cooker: 100 °C/ circulating air: 75 °C/ gas: see manufacturer) for approx. 2 hours. Keeps for several weeks if packed airtight