1. Previous day:  Have the mascarpone ready at room temperature and mix it with a little cream using a fork.  Once it is blended in, add the rest of the cream, mixing again, and put in a cool place till the following day.
   
2. The following day:  Crush the biscuits in a processor.  Mix with the melted butter and spread over the base of each sundae glass, pressing down well.
3. Slice the bananas, put in a dish and sprinkle with lemon juice to prevent discoloration.  Arrange evenly on top of the biscuits.
   
4. Cover with toffee spread, smoothing with the back of a spoon.
   
5. Whip the cream till firm (you can use an electric whisk at speed 1) and spread over the toffee, then smoothing the surface.
6. Decorate with finely sieved cocoa powder (here I’ve used a heart-shaped stencil).
   
7. If you don’t possess sundae glasses, you can equally well use a cake tin, making sure that the biscuit layer is well tamped down.
   
8. Refrigerate for 1 hour.
   
9. Bon appétite!
   

See recipe for Speculoos.