Mix butter in pieces, sugar and lemon zest in a mixing bowl. Fill lemon juice with boiling water to 60 ml, pour into the butter mixture and stir until creamy with the whisks of the mixer.
Mix 250 g flour and baking powder and knead in briefly. Wrap the dough in foil and chill for about 1 hour.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Line two baking trays with baking paper. Roll out the dough on a floured work surface. Cut out about 80 rabbits each. In between, knead the dough again and again, roll out again and cut out.
Spread the rabbits out on the trays. Bake in the hot oven on the lower rack for 7-9 minutes one after the other. Remove and let cool.
Mix icing sugar, milk and fruit spread to a smooth glaze. Spread half of each rabbit biscuit with it and place the remaining matching biscuits on top.