2) Cream the butter and sugar together until smooth.
3) Sift the cornflour and then add to the butter and sugar and mix together.
4) Put 2/3 of the dough into a ring mould and push down evenly to form a crust.
5) Pour the caramel from the tins into mould and sprinkle the rest of the dough on top.
6) Bake for 30 minutes in an oven at 180C/Gas 4. Take out and allow to cool.
7) For the garnish, whip the double cream with 1 tbsp sugar and the vanilla seeds. Put the whipped cream into a piping bag with a tip. Pipe rosettes on top of the tart and decorate with grated chocolate. Serve immediately at room temperature – do not put in the fridge.