Fill the tray with baking paper, and pre-heat the oven to 180 C° (356 F°)

Mix the ingredients of the dough, and divide it into two parts. Stretch them out into two 36x35 cm squares. Don't forget to sprinkle the surface with flour, because the doughs must be sticky.

Bake the doughs for 6-8 mins each.

Now we're starting the cream. Mix the pudding powders with the flour and cook it with the milk until the mixture thickers.

Take it off the cooker and pour the sour cream into it. Mix it well. Then leave the mixture until it's room temperatured.

Mix the butter with the powdered sugar and vanilla sugar, and then pour it into the pudding mixture. Mix them all together.

Pour the cream between the two layers of sponge cake, and gingerly press them together. Put it into the fridge and leave it for 12 hours. Then slice them and enjoy! :)