Make a kneading dough from the first ingredients. Refrigerate.
Roll out the dough thinly and cut out cookies with a round shape (approx. 4cm diameter) and place on a baking sheet.
For the topping, beat the egg whites until stiff. Add the lemon juice and gradually add 100 g of sugar. Carefully fold in the cardamom and walnuts and pour the mixture into a piping bag with a star nozzle and squirt rings on the outer edge of the cookies.
Baking time 10-12 minutes at 170 degrees.
Bring the jam to the boil while stirring, let it cool down a little and fill the middle of the cooled cookies.