For the crumble, knead all the ingredients together.
Then cut the rhubarb into small pieces, place in a pot, cover with water and simmer for a while. Add coconut blossom sugar to taste and stir in cornflour at the end to make the compote a little firmer.
Then put everything into a baking dish, spread the dough over it as a crumble and bake in the preheated oven at 180 degrees top/bottom heat for approx. 45 minutes.