Melt butter for the bottom. Fill cookies into a large freezer bag, close it and run a cake roll over it until the cookies are finely crumbled. Mix with the liquid butter and press into a porcelain mould (18 cm Ø) to form a base.
Place the mould in a cool place for at least 30 minutes.
For the brittle chop the nuts coarsely. Roast in a pan without fat for about 4 minutes while turning and remove. Add 3 tbsp. sugar to the pan and caramelise. Mix in nuts and cinnamon. Pour onto a piece of baking paper and spread as flat as possible (see
Mix sour cream and 60 g sugar. Whip the cream until stiff and let vanilla sugar trickle in. Fold into the sour cream. Peel and dice the banana. Add frozen berries to the sour cream.
Spread on the biscuit base. Chill for at least 3 hours. To serve, break the brittle into pieces and spread on the cream. Sprinkle with chocolate syrup (see right) as desired.