This intensely flavoured light-as-a feather mousse brings a bit of summer all year round – I usually freeze the glut of garden raspberries so that I can recapture summer in deepest winter. You will need a food processor/blender and an electric hand whisk, and 2-3 decent sized mixing bowls, one of which conducts heat. You'll need a large glass bowl (1.1 litres/2 pints) or 6 dessert glasses/ small Kilner jars to serve. The trick to this recipe is following the order/methods of combining the ingredients, so the mixture moves across from bowl to bowl as ingredients are added, ending up in the bowl that you used to whisk the egg whites in.

450g raspberries- reserve a few for serving

5 sheets of leaf gelatine – there are now vegetarian versions of this

4 eggs, separated

80g caster sugar

150ml double cream

• Whizz the raspberries in a food processor until blended to a smooth pulp. Place in a sieve above a bowl and push the pulp through with a metal spoon to remove the seeds. Set aside

• Meanwhile, place the egg yolks and caster sugar in a large bowl. Use an electric hand whisk to whisk the eggs and sugar for 4–5 minutes or until thick, pale and fluffy and when you lift up the whisk, a trail is left in the mixture. Stir the raspberry purée into the egg/sugar mixture. Set aside

• Soak the gelatine in a small heatproof bowl of cold water for 5 minutes until soft. Squeeze out the liquid from the gelatine and tip away all but 2 tablespoons of water. Put the gelatine into a large bowl with the 2 tablespoons of water. Set the heat conducting bowl on top of a saucepan of gently simmering water and stir for a few minutes until the gelatine is dissolved and runny. Remove from the heat and set aside to keep warm

• Whip the cream to soft peaks, then carefully fold into the raspberry mixture. In a clean, dry bowl, whisk the egg whites until stiff. Set aside

• Add a few spoonfuls of the raspberry mixture to the gelatine (not the other way round otherwise the gelatine might separate). Quickly stir in the remaining rasberry mixture. Make sure everything is well distributed. Stir 2 tablespoons raspberry mixture into the egg whites then gently fold in the remaining mixture

• Spoon into the large glass bowl or divide between the individual glasses, then chill in the fridge for a minimum of 4 hours until set. Serve straight from the fridge