Cook the rhubarb with the sugar.
Remove the unwanted liquid and soak the bread slices in it.
Melt the butter, add the flour and cook.
Add the cream and let it thicken.
Beat the egg yolks, add the vanilla and pour the gravy while stirring.
Beat the egg whites until stiff peaks form and fold in the gravy and rhubarb.
Line a buttered soufflé pan with the bread slices.
Pour the rhubarb soufflé over the bread slices.
Cook in the oven at 180°C (350°F) for about one hour.
Serve with fresh cream.