Mary’s Viennese whirls
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 the boil over a low heat. When the sugar is melted, increase the heat and boil for a further 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.
For the biscuits, preheat the oven to 190C/170C Fan/Gas 5. Line 3 baking sheets with non-stick baking parchment. Using a 5cm/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.
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.
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.
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.
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.
If your kitchen is warm and you have time you could try placing the whirls in the fridge for 15 minutes before baking. This will help them hold their shape while cooking.