Preheat the oven to 200° traditional heat. Generously butter a ceramic or glass mold, mine is oval and measures 30X21cm.
Wash the rhubarb stalks and cut them diagonally into pieces of approximately 2 cm. NB: if your rhubarb stalks are thick, you can peel them first to reduce the stringy side.
In a pan over medium heat, melt the butter and add the powdered sugar. Place the pieces of rhubarb and heat for a few minutes while stirring: the pieces of rhubarb should soften and release a little juice. Remove into a container, and set aside for later.
In a large bowl, whisk the eggs and brown sugar. Add the vanilla then mix.
Sift the flour with the salt and cinnamon then add it to the dough in several batches, whisking so as not to have lumps.
Finally, incorporate the liquid cream and the milk in several times to obtain a smooth and liquid batter like pancake batter.
Pour this dough into the mold. Add the rhubarb pieces.
Bake for around 35 minutes (this varies depending on the oven). The sides of the clafoutis should be nicely browned. The center should bounce slightly when touched.
The clafoutis can be enjoyed warm or cold, depending on your preferences... You can sprinkle with a little icing sugar before serving (optional).
Notes
This rhubarb clafoutis can be kept at room temperature if tasted the same day, otherwise it must be placed in the fridge, where he keeps about 2 days.