1. Heat up the milk (50°C) and give it in a big bowl. Dissolve the sugar and melt the butter in the milk.
2. Add the lemon zest, egg, salt and yeast. Mix till merged.
3. Add the flour and mix till the dough is firm.
4. Leave the dough to rise for 1 ½ hours.
5. Half the plums and remove the seed. Make sure that the plum halves stay attached to each other at one part.
6. Mix the ingredients for the crumbles (flour, sugar, cinnamon, salt, butter) in a bowl and kneed till you have a crumbly dough. Alternatively you could also use a kitchen machine with using a
7. When the dough is ready to use, take a baking tray and cover with baking paper.
8. Evenly spread the dough over the baking tray and spread the plums over it.
9. Cover the plums evenly with the crumble mixture. Sprinkle occasionally with a bit of sugar and cinnamon mix.
10. Bake at 180°C (hot air) for 40 minutes, till the crumbles have a golden color.
Tip: leave the cake to rest till the next day to have a full aroma.