1) First of all, the oven must be preheated to 160 C.
2) A spring-form cake pan (22 cm) should be greased and lined using baking paper.
3) Place orange zest, brown sugar and butter in a bowl and beat for 5 minutes using an electric mixer. (You can stop when the mixture becomes fluffy and pale).
4) Eggs have to be added 1 at a time and they should be beaten well after each addition.
5) Sour cream, cinnamon and combined flour have to be floured in using a large metal spoon in alternating batches.
6) The rhubarb has to be stirred in.
7) It has to be spooned into the prepared pan and the surface has to be smoothed.
8) The extra rhubarb should be arranged on top.
9) Raw sugar has to be sprinkled in.
10) It should be baked for 1 hour 15 minutes. (Make sure that when a skewer is inserted onto the center the cake, it comes out clean).
11) You have to leave it in the pan for 10 minutes to cool. 1
2) The cake has to be released from the pan and transferred to a wire rack so that it cools completely.
13) Icing sugar must be dusted with.
14) You have to slice and then, it can be served warm.