Separate the egg. Cover the egg white and chill. Briefly mix flour, cold butter in pieces, sugar, vanillin sugar, salt, egg yolk and 3-4 tablespoons of ice water with the dough hooks of the hand mixer. Pour onto the work surface and knead into a smooth dough with your hands. Wrap in cling film and chill for 1 hour. Roll out the dough 1/2 cm thin on a floured work surface.
Cut out little lambs (large: 11 cm, small: 8 cm) and place them on 2 baking trays lined with baking paper. Roll out the rest of the dough again. Cut out more lambs. Bake the trays one after the other in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 15 minutes. Let the biscuits cool down on a cake rack. Mix egg white, icing sugar and lemon juice with the whisk of the hand mixer. Quarter the icing. Leave one part white. Colour the rest of the icing pink, light yellow and light green. Put 2 tablespoons of icing of each colour into a small piping bag or freezer bag. Cut off small corner. Spread biscuits with icing in different colours.
Leave one part white. Colour the rest of the icing pink, light yellow and light green. Put 2 tablespoons of icing of each colour into a small piping bag or freezer bag. Cut off small corner. Spread biscuits with icing in different colours. Leave to dry. Spray pattern on the biscuits and let dry. Decorate as you like with ribbons and bells