Wash, clean and cut the rhubarb into pieces. Put 50 g sugar, rhubarb and 50 ml water in a pot and bring to the boil. Mix the groats powder with a little water and pour it into the rhubarb while stirring. Let simmer for about 2 minutes. Put compote into a bowl and cover with cling film directly on the surface. Let it cool down.
Stir mascarpone, quark, milk, vanillin sugar and 2 tablespoons of sugar until smooth. Coarsely chop the lady fingers as desired and place them with Amaretti in four portion bowls. Drizzle with liqueur. Add the compote and chill until serving. Pour mascarpone cream onto the compote and serve lightly dusted with cocoa. Decorate with mint as desired