Whip cream until stiff, mix mascarpone, quark, sugar and vanilla sugar, fold in cream.
In a square casserole dish, spread approx. 3 tbsp. of the cream and place a layer of speculoos on top. Spread the berries on top (can be prepared well with the frozen fruit the evening before, it will soak through well).
Spread the remaining cream on top and cover with speculoos. Chill for 4-5 hours or overnight.
Sprinkle with icing sugar before serving. It looks especially nice if you use a stencil to sprinkle stars of cocoa.