Step 1
Preheat the oven to 170C / 340F/ Gas Mark 3.

Step 2
Prepare a baking tray with greaseproof paper.

Step 3
To make the dough, rub the flour, Trex, sugar and crushed vanilla pod together. Knead until the dough is smooth. Roll the dough in to a ball, wrap in cling film and chill for 15 minutes.

Step 4
Roll out the dough on to a floured surface until around 12mm thick. Use a pastry cutter to cut out 8 circles (circa 10cm diameter) and use a knife to cut out a small window in the middle of four of them. If you make more, cut a window in half of them.

Step 5
Bake in the oven at 170C for 15 minutes

Step 6
Once cool, spoon a little cream on to the top of the whole biscuit side before topping with jam. Place the window side of the biscuit on top before leaving to set.