Note: the quantities in the text refer to a preparation with three hundred g of rhubarb! Be sure to weigh the prepared rhubarb for the flans, then dice it into small cubes. Make two-thirds of the rhubarb cubes into puree with the syrup and half of the sugar with the lid closed. Pour into a sieve, collect the juice, squeezing any remaining rhubarb very well, it will not be used again.
Return the rhubarb juice to the frying pan and boil to 1 dl.
Stew the remaining diced rhubarb with the other half of the sugar, uncovered, until just barely tender, remembering that it will cook slightly as it cools. Drain into a sieve, reserving the juice, 1/2 dl to the thickened rhubarb juice form.
Bring cream, milk and vanilla sugar to a boil. Remove from heat.
Soak the gelatine in cold water until it has collapsed. Squeeze it out and let it melt in the hot cream mixture. Then add the reduced rhubarb juice and the diced rhubarb.
Fill the mixture into portion molds and let cool for at least 120 minutes.
For the compote, cut the rhubarb into pieces. Place in a frying pan with the jam and steam until just tender with the lid closed.
Cool.
To serve, place the ramekins with the flans briefly in hot water, loosen the rim and turn the puddings out onto plates. Serve with compote.
Tip: the flans can be stored in the refrigerator for up to 4 days.