• Heat oven to 180°c
• Line three baking trays with baking paper (or bake in batches). If desired, you can mark out 12 circles on each baking sheet as a guide to help you when piping the biscuits later on. I marked out 12 circles with a pencil using a 4cm round cutter. Make sure you turn the baking paper over and use the reverse side though!
• In a large bowl, beat together butter and icing sugar until pale and fluffy.
• Sieve in flour, cornflour and baking powder and then mix everything together well.
• Transfer mixture to a piping bag with a large star nozzle. Pipe onto the lined baking tray inside the circles - start from the outside of the circle and then work your way to the center.
• Place the trays in the oven and bake for 12 minutes, or until the biscuits are turning golden.
• Remove from the oven and allow to cool completely.

For the Buttercream:

• While your biscuits are cooling, prepare your buttercream.
• In a large mixing bowl, beat butter, icing sugar and vanilla extract until light and smooth.
• Transfer to a piping bag with a medium round nozzle.

To Assemble:

• Spoon a teaspoon of the jam onto the inside of one biscuit.
• Pipe a circle of buttercream on top of the jam.
• Place another biscuit on top of the buttercream and sandwich together.
• Dust with a little icing sugar if desired - then enjoy!