For the crumble, mix butter (small pieces), flour and sugar.
Wash rhubarb and cut in small pieces.
For the dough, wisk soft butter, sugar and salt.
Add eggs one by one, whilst mixing.
Mix flour and baking powder and fold in.
Mix in yogurt and milk.
Spread dough evenly on baking tray with baking paper.
Scatter rhubarb on dough.
Top with crumble.
Bake in preheated oven at 180° C for 40 minutes.
Variation:
Use cherries, apricots or plums instead of rhubarb.