Mix all the dry ingredients together in a bowl. Then work in the butter with a fork until everything is completely mixed and the dough has a crumbly consistency.
Now mix all the liquid ingredients with the egg and orange peel in another bowl and mix well with the dry ingredients at the end.
Put the dough in a loaf pan.
For the crumble mix the sugar, breadcrumbs and orange peel, then work in the butter again with a fork and spread the slightly sticky crumble on the cake.
The whole thing is then placed in the hot oven at 190 ° C for about 30 minutes.