For the groats, stir 4 tablespoons of nectar and starch until smooth. Boil up the rest of the nectar, half of the frozen berries, 1 vanilla sugar and 2 tablespoons of sugar. Stir in the starch, bring to the boil again and simmer for about 1 minute while stirring.
Fold in the rest of the frozen berries. Remove from the heat and allow to cool for about 30 minutes, stirring frequently.
Cut the bread into small cubes. Heat butter in a pan. Roast the bread cubes all around. Sprinkle with brown sugar and allow to caramelize slightly while turning. Remove.
Beat the sour cream and cream until stiff, adding 3 vanillin sugar and 1 tablespoon of sugar. Put the bread in a large container. Drizzle orange juice over it. Spread the sour cream on top, add the groats.
Allow to soak for at least 45 minutes.