Preheat the oven to 225 degrees celsius (430 degrees Fahrenheit).
In a large bowl, whisk butter, sugar, and salt until it has a fluffy consistency. Add eggs and milk and stir well. Mix flour, vanilla sugar, and baking powder, and carefully stir it into the butter mixture.
Take half of the dough and put it in a new bowl. In one bowl, add the dried blueberries and in the other bowl add the fresh blueberries. The white chocolate is chopped and divided equally in both bowls. Gently stir the chocolate and blueberries into the two doughs.
Shape small portions of dough using two tablespoons and spread them out on parchment paper at a good distance from each other.
Bake both types of cookies in the oven for approx. 7-8 minutes, depending on the sizes.