Whizz the Oreos in a food processor to fine crumbs.

Pour the melted butter in, with the motor still running, and whizz briefly until the mixture is the texture of wet sand.

Divide among 2 x 12 cm loose bottomed tart tins and press into the sides. Chill for 10 minutes.

Peel and slice the banana, then put a layer of banana slices in each tart tin. Warm caramel sauce in the microwave until just pourable – then divide between tarts and leave to cool.

Pour the cream into a bowl, add the cream of tartar and ½ tbsp icing sugar.

Stir, taste and add more sugar if you like, but take it easy, the rest of the tart is very sweet.

Whip the cream to soft peaks and transfer to a piping bag fitted with a star nozzle. Pipe swirls over each tart or spoon the cream on top and make swirls and peaks using the back of the spoon.

Chill until needed, then serve dusted with cocoa powder.

I assembled the tarts in glasses for each portion
and used caramel treat as thick caramel.