Divide the raspberries among 6 ramekin dishes. Put the egg yolks and sugar in a large bowl and set it over a saucepan of simmering water, making sure the water does not touch the bottom of the bowl. Whisk the egg yolks and sugar until light and foamy, then gradually whisk in the Champagne, then the cream. Continue whisking for about 20 minutes until the custard is very thick and bubbly.
Pour the custard over the raspberries and leave to cool at room temperature for about 1 hour. Sprinkle the tops with the sifted icing sugar and caramelize with a blowtorch (or under a hot grill). Serve within 20–30 minutes, decorated with a few extra raspberries lightly dusted with icing sugar.