Ingredients - For the Biscuits:
200g slightly salted butter, softened
50g icing sugar
2 tsp vanilla extract
200g plain flour
2 tsp cornflour
1/2 baking powder

Ingredients - For the Filling:
100g butter, softened
170g icing sugar
1 tsp vanilla extract
50g Raspberry Jam (Recipe here)

Method:
Step 1: Heat oven to 180˚C and line 2 baking sheets with baking parchment.

Step 2: Put the butter and icing sugar in a large bowl and beat with an electric hand whisk for about 5 mins until pale and fluffy.

Step 3: Add the vanilla extract and beat again until fully combined.

Step 4: Sift in the flour, cornflour, and baking powder, and fold into the mixture using a spatula until combined. The texture will be a little tacky but this is what you want it to be like.

Step 5: Spoon the dough into a piping bag fitted with a large star-shaped nozzle.
Pipe swirly circles 5cm diameter onto 2 baking sheets making sure there are 3cm spaces between each swirl so they have some room to bake.

Step 6: Bake for 10-12 mins, swapping the trays over halfway through the cooking time so the biscuits are evenly baked, until pale golden and cooked through.

Step 7: Leave too cool on the baking sheets for a few mins, then transfer to wire racks.

Step 8: Next, while the biscuits are cooling, make the filling. Put the softened butter in a large mixing bowl and add the icing sugar. Stir together first with a wooden spoon then switch to electric beaters to get the buttercream fluffy and smooth.

Step 9: Then add the vanilla extract and whisk for another minute so that it is combined. Put the buttercream into a piping bag with a small nozzle.

Step 10: Turn the biscuits over so their flat side is facing up then pipe buttercream over half of the biscuits and spread a little jam on the rest. Sandwich a jam-covered biscuit together with a buttercream one and repeat until all the biscuits are used up.