Raspberry-chocolate bombe Alaska

1.For raspberry sorbet, place a 2-litre pudding mould in the freezer to chill (about 30 minutes). Purée raspberries in a blender. Stir sugar and 250ml water in a saucepan over medium-high heat until sugar dissolves (3-5 minutes), then add a third of the raspberry purée. Stir to combine (1-2 minutes), then add to remaining raspberry purée and pass through a sieve to remove some of the seeds. Process in an ice-cream machine, then press sorbet into chilled mould to line base and sides, and return to the freezer until starting to firm (1-2 hours; you may need to press sorbet more evenly into mould once it has firmed up).

2.For chocolate ice-cream, place 160gm chocolate in a large bowl and set aside. Bring milk and half the cream to just below boiling point in a saucepan over medium heat. Meanwhile, whisk yolks and sugar in a bowl until pale (2-3 minutes). Whisking continuously, gradually add milk mixture, then transfer mixture to a clean saucepan and stir continuously over medium heat until it thickly coats the spoon (5-6 minutes). Strain through a sieve into bowl of chocolate, stir until chocolate melts, then stir in remaining cream and refrigerate to chill. Churn in an ice-cream machine, then fold in remaining chocolate, spoon into bombe mould, smooth top and freeze.

3.For cake, preheat oven to 180C. Butter and flour a 21cm-diameter round cake tin and line the base with baking paper. Beat butter and sugar in an electric mixer until pale (5-6 minutes). Add eggs one at time, beating well between additions, fold in flour in batches, then spoon batter into prepared cake tin, smooth top and bake until golden and the centre springs back when lightly pressed (15-20 minutes). Turn out onto a wire rack to cool, then trim to fit snugly over top of bombe and trim top flat (reserve trimmings). Place cake on top of bombe and freeze until ice-cream is set firm (4 hours or overnight). Turn bombe out of the mould, crumble reserved cake trimmings and scatter crumbs over bombe (this helps the meringue to adhere) and return to freezer until very firm and ready to serve (2-3 hours; this can be done a day ahead).

4.For Italian meringue, bring sugar and 200ml water to the boil in a small saucepan, stirring continuously with a wooden spoon until sugar dissolves. Reduce heat to medium and brush down sides of pan with a clean, wet pastry brush to remove sugar crystals. Cook, without stirring, until syrup reaches 115C on a sugar thermometer (soft-ball stage; 10-15 minutes), then start whisking eggwhites with cream of tartar in the clean, grease-free bowl of an electric mixer on medium speed to soft peaks. When sugar syrup reaches 121C (hard-ball stage), increase mixer speed to high and, with motor running, gradually pour syrup into eggwhite and beat at medium speed until cool, thick and glossy (15-20 minutes).

5.To serve, working quickly, spread meringue over bombe and scorch it with a kitchen blowtorch.