Method

1. For the raspberry jam, heat the raspberries, sugar and 3 tablespoons water in a large, heavy-based saucepan over a low heat for 2-3 minutes, or until the sugar has dissolved. Increase the heat and cook the mixture for a further 6-8 minutes, or until it has thickened enough to coat the back of a spoon.

2. Set aside 75g/2½oz of the jam to use in the Swiss roll. Pour the remaining jam into hot, sterilised jars, seal, and set aside to cool.

3. For the sponge, preheat the oven to 190C/170C Fan/Gas 5. Line a 38x25cm/15x10in Swiss roll tin with baking parchment.

4. In a large bowl, whisk together the eggs, sugar and half the vanilla seeds until very light, thick and fluffy. Fold in the sifted flour using a metal spoon, trying to retain as much air as possible in the batter.

5. Pour the batter into the prepared tin and smooth the surface using a spatula. Bake in the oven for 10-12 minutes, or until the sponge has risen and is just firm to the touch (it should spring back when pressed lightly with a finger).

6. Place a clean, damp tea towel that is slightly bigger than the Swiss roll tin onto a work surface and dust it with caster sugar. Turn the sponge out onto the tea towel, then carefully peel away the baking parchment.

7. With the longest edge of the sponge facing you, roll up the sponge firmly but gently in the tea towel, making the roll as tight as you can. Carefully unroll the sponge and leave to cool completely.

8. To assemble the Swiss roll, whip the double cream with the remaining vanilla seeds until firm peaks form when the whisk is removed.

9. Spread the raspberry jam all over inside of the cooled sponge, leaving a 2cm/1in border at the long edge that’s furthest from you. Spread most of the cream on top of the jam.

10. Roll up the sponge again, starting at the long edge closest to you (as before) and using the tea towel to guide you. Aim to make the Swiss roll as tight as possible without squeezing out the filling.

11. Using the tea towel, lift the Swiss roll onto a serving plate, with the seam against the plate. Dust with a little more caster sugar and garnish with raspberries and the mint or lemon verbena sprigs. If desired, decorate the top of the Swiss roll with quenelles of the remaining whipped cream, then sprinkle with the pistachios, if using.