Rhubarb clean, rinse and cut into 4 cm long pieces. Pour maple syrup and leave covered for half an hour to infuse juice. Then simmer the rhubarb in the syrup on a low gas flame for 3 to 5 minutes. Remove with a skimmer and set aside to cool. Boil the raspberries in the stock, make into a puree, pass through a sieve and set aside to cool. Mix crème fraîche with liqueur, set aside to cool. Mix buckwheat flour with honey, crumbled yeast, one eighth l of lukewarm tap water. Add salt and eggs and let the dough rise for 1500 minutes. Then bake 12 small blinis in hot clarified butter. Spread the raspberry sauce on 4 serving plates, drizzle crème fraîche around it. Pull inside and out with a small stick. Place the blinis in the center, spread with rhubarb pieces and place on the spot on the table.