Shortbread cookies with jam

I love shortbread cookies, and these are my favourite one , the addition of homemade jam make them taste amazing.
Ingredients:
- 400g cake flour
- 250g butter (room temperature)
- 3 tablespoons powdered sugar
- 1 pack of vanilla sugar
- zest of half a lemon
- 2 tablespoons potato starch
- 3 yolks
- 1/2 teaspoon salt
- favorite jam
Recipe:
- Using an electric mixer, mix together soft butter and sugar, add yolks and mix again,
- Sift the flour, add vanilla sugar, zest of lemon, potato starch and salt, whisk everything together,
- Mix dry and wet ingridedns until dough starts to form,
- Heat the oven to 180 degrees, line a cookie sheet with parchment paper ,
- Form small balls out of the dough and place them on parchment paper. With the end of a wooden spoon make a indention in each ball,
- Fill each cookie with jam,
- Bake for about 20 minutes.

