I had a German friend who made one like that with plums. It was good! And so different from American desserts that tend to be SO sweet.Here's the recipe if you want to make it too!
[Metric measurements]
100 gram flour
3 gram baking powder
125 gram butter (i use full fat)
25 gram custard
2 big eggs (duck)
some orange juice (any juice will do, amount of approx. half an orange)
a little vanilla
Mix everything until it is a smooth dough and put it in a baking tray (22-26cm)
Take and clean 3/4 rhubarb stems and cut them in pieces (approx. 5 cm)
push all pieces inside the dough (you will still see the top parts of the stems.
bake 20 minutes on 200 degrees Celcius.
When it comes out of the over, put ginger jelly on the top. so it stays moist. (any jelly will do)
This recipe is very forgiving. so feel free to change the juice, vanilla, jelly...
I already tried:
Adding sugar on top before baking: not a better taste. gives a little bite.
Adding a pinch of salt: you can leave it out
Adding partly whole grain flour: up until 20% it will be fine, 30% or above you will loose the smooth structure.
Good luck!