Preheat the oven to 100C/200F/Gas ¼. Line a baking tray with parchment paper or a silicone mat.
Place the egg whites into a clean glass bowl and whisk until they form soft peaks when the whisk is removed from the bowl..
Whisk in the caster sugar a spoonful at a time until the mixture is glossy and forms stiff peaks.
Take one third of the meringue mixture out of the bowl and place into a piping bag.
Fold the raspberries into the remaining meringue and place eight spoonfuls of the mixture, each about 7.5cm/3in wide, onto the baking tray to make the wings.
With the reserved meringue mixture, pipe four long neck and head shapes onto the mat alongside the wings and bake in the oven for 1½ hours. Remove from the oven and let cool completely.
Place the double cream into a bowl with the vanilla seeds, whisk until it forms stiff peaks then gently fold in the strawberries.
Sandwich pairs of the “wings” together with the strawberry cream, carefully place the “necks” into the cream to complete your swan shape and serve immediately.