Spread oil on a tart mould with lift-off base and smooth rim (approx. 23 cm Ø). Put the biscuits in a large freezer bag, close the bag. Finely crumble the biscuits with a dough roller.
Heat the butter and mix well with the cookie crumbs. Spread the crumb mixture into the tin and press it to an even base with a rim. Chill for at least 1 hour.
Roughly chop the chocolate and melt over a warm water bath. Whip cream and sour cream separately, with a packet of vanilla sugar stiffly in each case. Mix cream and sour cream.
Peel and slice the bananas and mix them with lemon juice. Carefully remove the biscuit base from the mould and lift it onto a cake plate. Cover the base with banana slices. Spread the caramel spread in blobs on top.
Spread with sour cream-cream.
Spread warm chocolate over the cream, spread it in a circle with the back of a spoon. Chill for about 30 minutes.