Mix 250 g butter, the flour, and water together in that order using a fork and then your hands. Divide the dough into 6 balls and refrigerate for 40 to 60 minutes.
Working one ball at a time, roll each portion very thin, about 1 to 2 mm, on a floured surface.
Transfer each layer to a greased baking sheet and bake at the oven's maximum temperature for about 5 to 7 minutes, until baked through. Cool all 6 layers.
For the cream, whip the condensed milk with 200 g butter until smooth. Grind the walnuts.
Stack the cake layers, alternating cream with cranberry or lingonberry jam and ground walnuts.
Finish the top with cream, jam, and walnuts. Let the cake soak for 30 to 60 minutes, then refrigerate before slicing.
