Measure out the oatmeal and set aside. Put the remaining ingredients, except for vanilla sugar, in a pan and bring to a boil over medium heat. Simmer for 4 minutes, stirring constantly. Then add the vanilla sugar and the oat flakes. Mix well. All oatmeal should be covered with the mass.
Cut 15 cookies with the help of a tablespoon and spread them on a piece of baking paper. Put the cookies in the freezer for about 6 hours.