First knead the dough with the flour, mineral water and salt Roll out a rectangular shape from the dough and coat it with half of the butter or margarine. Roll out the dough by forming a cube and leave it in the freezer for 20 minutes to harden. Roll out the dough into a rectangular shape 1 cm thick. Apply the other half of the margarine or butter and fold the dough back into a cube. Leave for 20 minutes in the freezer to rest. During this time, mix the ingredients for the filling (cherries, starch, sugar, vanilla and cinnamon). Roll out the dough and cut into heart-shaped pieces with the help of a cake mould. In the middle of each second formed heart, cut a small circle or small heart with a smaller mold. Place the filling in the middle of the hearts without holes. Cover the heart with an already formed hole and press the ends with a fork. Place the prepared heart-shaped pastries in a paper-lined pan and bake for about 15-20 minutes at 180 degrees.