Preheat the oven to 180C/350F/Gas 4.
For the rhubarb fool, whip the double cream in a bowl until soft peaks form when the whisk is removed. Whisk in the icing sugar, yoghurt, strawberry liqueur and vanilla seeds until well combined.
Place the rhubarb onto a baking tray. Sprinkle with sugar and add the star anise and cinnamon stick. Bake in the oven for 5 minutes, or until the rhubarb is tender.
Allow the rhubarb to cool slightly, and then fold into the fool mixture until well combined.
For the biscuits, cream the butter and sugar in a bowl until light and fluffy.
Stir in the egg and golden syrup. Add the flour, baking powder, ground ginger and stem ginger and mix until well combined.
Roll the mixture into golfball-sized shapes and bake in the oven for 8-10 minutes, or until golden-brown.
Spoon the fool mixture into pretty glasses and serve the biscuits alongside.