The Polish recipe calls for budyn, a powdered custard which might be tricky to find outside of Poland, so I used thick pouring custard instead. You can bake the pastry form-free or if you happen to have a 30cm x 20cm cake tin, use that. You can work with the dough ball while still warm, for flaky pastry, allow the dough ball to cool completely to room temperature before adding eggs. This will help create the layers.