Mix the curd cheese with the lemon zest, yolk and sugar until creamy. Soak the gelatine in cold water, squeeze it out and heat it in a little lemon juice on the stove. Combine the curd cheese mixture and gelatine (first warm up a little of the curd cheese mixture and then pour over the rest of the cheese to prevent the gelatine from forming lumps). Whip the whipped cream until stiff and carefully fold it into the curd mixture. Chill in the refrigerator for a few hours.
For the blackberry sauce, caramelize the sugar in a pan. Deglaze with the currant juice while stirring, then add the cinnamon stick, allspice, lemon juice and lemon peel and simmer gently for 5 minutes. Then take out the cinnamon stick. If the liquid is too thin, add a little mixed cornstarch and thicken. Wash the blueberries, pat dry and stir into the sauce. Take the pot off the stove and let the sauce steep.
Cut out dumplings from the curd mixture and serve on the cold or lukewarm blackberry sauce.