I love to make a crumble (Streusel) cake with currants, jostas should work as well. You use the same dough for bottom and crumble and use pepitas in the mix.
Then of course jams are delicious if you use tart berries like josta.
Popular in northern Europe and Scandinavia is a dessert made with different (red) berries, served with vanilla sauce or cream.
In German it is called Rote Grütze, usually thickened with starch.
https://de.wikipedia.org/wiki/Rote_Gr%C3%BCtze
This danish page is in English:
Danish red berry pudding
Very refreshing in summer!
I am only one, but still I am one. I cannot do everything, but still I can do something; and because I cannot do everything, I will not refuse to do something that I can do. (E.E.Hale)