• For the crumble, mix the flour, sugar and butter and knead until crumbly. Peel the rhubarb and cut into small pieces. Place muffin cups into a muffin baking tray. Break the chocolate into small pieces and melt in a bain-marie.

• Preheat the oven to 180˚C. In a large bowl stir together the eggs, sugar, milk, oil, a pinch of salt and the vanilla pod seeds. Add half the melted chocolate (100g) and stir in well. Mix the flour and baking powder with the cocoa, sieve over the mixture, and then fold in loosely with a large spoon.

• Put the dough into the muffin cases. Press the rhubarb pieces into the dough, and then spread over the crumble, before baking in the oven for 20–25 minutes.

• Allow the baked muffins to cool down before pouring the remaining melted chocolate (100g) over them.