Ingredients for its dough:
I'm afraid that's not what kruszonka (shortcake/crumbs) is, i.e the top part in a Polish placek. Your recipe has way too little butter and way too little sugar and it appears that your cake will have the same doe for the bottom and for the top.
Shortcake is probably the easiest doe to make:
100 to 200 g flour
100 g butter
100 g sugar
Mix sugar with flour. Add melted butter and work everything into doe. Sprinkle the top of the cake and bake. In my experience, the shortcake topping is best added at a later stage of the baking process as to avoid burning.
That very same recipe was used for Polish klawisze (shortcake cookies). Proportionally more sugar would make them harder, and they were topped with a mixture egg white and powdered sugar. The mixture need to be beat up real well, as in on of those trick where when done you turn the bowl upside down and the mixture will not fall out of the bowl. These are best baked with the bottom heating element on and the top off. That prevents the sugar in the top glaze from burning and becoming brown.
When the shortcake is added to top the cake will depend on how the type of the product the heat is applied during baking: top only, bottom only top and bottom. Some newer stoves will have a setting for choice baking which uses mostly bottom element with the top element operating ever now and then, or at lover temps. The process may sometimes be tricky with yeast (instead of baking powder) based cakes as these are best left undisturbed from start to finish.