Mary Berry's Viennese Whirls

Ingredients

For the jam

• 200g (7oz) raspberries
• 250g (9oz) jam sugar

For the biscuits

• 250g (9oz) very soft unsalted butter
• 50g (1¾oz) icing sugar
• 225g (8oz) plain flour
• 25g (1oz) cornflour

For the filling

• 100g (3½oz) unsalted butter, softened
• 200g (7oz) icing sugar, plus extra for dusting
• ½ tsp vanilla extract

Instructions

1. 1
   For the jam, put the raspberries in a small, deep-sided saucepan and crush them using a potato masher. Add the sugar and bring to boil over a low heat. When the sugar is melted, increase the heat and boil further for 4 minutes. Remove from the heat and carefully pour into a shallow container (pass it through a sieve if you'd rather not have seeds in your jam). Leave to cool and set.
2. 2
   For the biscuits, preheat the oven to 375F. Line 3 baking sheets with non-stick baking parchment. Using a 2in round cutter as a guide, draw 8 circles on each sheet of paper, spaced well apart. Turn the paper over so the pencil marks are underneath.
3. 3
   Measure the butter and icing sugar into a bowl and beat until pale and fluffy. Sift in the flour and cornflour and beat well, until thoroughly mixed. Spoon the mixture into a piping bag fitted with a medium star nozzle. Pipe 24 swirled rounds (not rosettes), inside the circles on the baking sheets.
4. 4
   Bake in the centre of the oven for 13—15 minutes, until a pale golden-brown. Cool on the baking sheets for 5 minutes then carefully transfer to a wire rack to cool completely and harden.
5. 5
   For the filling, measure the butter into a bowl and sift the icing sugar on top. Add the vanilla extract and beat with a wooden spoon or an electric whisk until very light and smooth. Spoon into a piping bag fitted with a large star nozzle.
6. 6
   Spoon a little jam onto the flat side of 12 of the biscuits and place jam-side up on a cooling rack. Pipe the buttercream over the jam and sandwich with the remaining biscuits. Dust with icing sugar to finish.