Lemon cookies that melt in your mouth. desserts to make at home

1 egg yolk
30 g cornstarch
70 g sugar
40 g butter
10 ml lemon juice
300 ml milk
5 g vanilla sugar
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100 g butter
150 g sugar
50 ml milk
1 egg
280 g flour
7 g baking powder
10 g vanilla sugar
pinch of salt and turmeric
lemon zest
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50 ml lemon juice
20 ml water
10 g sugar
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bake at 180°C for about 15-20 minutes