Cream 250 g butter, vanilla sugar and 80 g icing sugar with the whisks of the mixer. Mix 375 g flour and starch. Using the whisks of the mixer, briefly stir into the butter-sugar mixture.
Then quickly knead into a smooth dough with floured hands.
Preheat oven (electric cooker: to 175 °C/circulating air: 150 °C/gas: see manufacturer). Line two baking trays with baking paper. With floured hands, shape the dough into approx. 80 almost cherry-sized balls. Place them on the baking trays with some distance between them.
Dip a fork in flour and press the balls a little flatter with it. Bake in a hot oven for about 12 minutes one after the other. Leave to cool on the trays.
For the filling, wash the lemon hot, dab dry and finely grate the peel. Squeeze the lemon. Whip 100 g butter and 100 g icing sugar with the whisk of the mixer for about 5 minutes until white-creamy.
Stir in lemon zest and 2 teaspoons of juice. Pour cream into a freezer bag. Cut off one corner. Spray on the bottom of about 40 cookies. Put them together with the rest of the cookies. Chill for at least 30 minutes.
Shelf life approx. 1 week when chilled.