In a large bowl, stir together 4 cups of flour, baking soda and 1 cup of confectioners' sugar. Cut in 1/3 cup of butter using a pastry blender or by pinching between your fingers until the mixture is crumbly. Make a well in the center, and pour in the eggs, honey and sour cream. Stir until dough comes together.
Divide into 4 equal pieces. Roll each piece of dough out into a equally large rectangle about 1/8 inch thick. Place on the prepared cookie sheets.
Bake for 15 minutes in the preheated oven, or until firm and lightly golden. Bake in batches if you do not have enough room for all of the sheets at once. Set aside to cool.
In a saucepan over medium heat, stir together 2 cups of confectioners' sugar, vanilla sugar, and 1/4 cup of flour. Gradually mix in the milk until smooth. Cook and stir until thick and dense like porridge. Remove from the heat, and stir in the butter. Allow to cool.
When the pastry sheets and filling are both cool, spread 1/3 of the filling onto one sheet. Top with another sheet, and another third of the filling. Repeat, once more, ending with the final sheet of pastry on top. Slice into rectangles, and dust with confectioners' sugar before serving.
Original recipe yield: 12 servings.