This is a pretty classic Swedish cake, and oh so good. It's chewy and cakey (not fluffy!) and pleasantly sweet-sour from the tangy rhubarb. It's topped with pearl sugar, which I imagine isn't that easy to find in some places, but it's very common here.
Serve it with vanilla custard, whipped cream or ice cream.
Note that this is a pretty small cake.
150 g sugar
90 g flour
1/2 tsp baking powder
rhubarb - I used ten very slender stalks, maybe about 200 gram.
50 g butter, cold
2-3 tbsp pearl sugar
Cut the rhubarb into 1-cm pieces.
Beat together eggs and sugar until pale and very fluffy. Fold in the flour and baking powder. Pour into a lined springform pan, about 24 cm in diameter. The batter might not look like it's enough - that's ok.
Sprinkle with the rhubarb pieces, really press them into the batter. (Which will now fill the pan a bit better.)
Slice the butter very thinly (A cheese slicer is ideal) and place the slices on top of the cake. Sprinkle with pearl sugar.
Bake at 175°C for about 25 minutes. It should be golden and start to pull away at the edges.
Serve, warm or at room temperature.