Any stone fruit works well for this cake - white or yellow peaches, nectarines or even plums. It can easily be made ahead and if you don't own a blowtorch to toast the meringue, don't worry; just keep the top snowy white.
- 100 gm ginger crisp biscuits (see note)
- 40 gm butter, melted
- 600 gm frozen raspberries, partially defrosted
- 400 gm frozen strawberries, partially defrosted
- 220 gm (1 cup) caster sugar
- 50 gm powdered glucose (see note)
- 6 peaches, halved, stones removed
- 280 gm caster sugar
- 600 gm thick Greek style yoghurt
- 1 tbsp lemon juice
- 110 gm (½ cup) caster sugar
- 2 eggwhites
- 1Line the sides and base of a 20cm-diameter round cake tin with removable base with baking paper. Process ginger crisps to a coarse crumb in a food processor, stir in and a pinch of fine sea salt flakes, then press evenly into the base of the cake tin and refrigerate to set.
- 2For berry sorbet, blend berries in a blender or food processor until smooth, then strain through a fine sieve. Combine half the purée, sugar, glucose and 120ml water in a saucepan, bring to the simmer over medium heat, stir to dissolve sugar and set aside to cool (30 minutes). Transfer sugar mixture to a bowl, add remaining purée, and refrigerate to chill (3 hours). Churn in an ice-cream machine until frozen, then spread half the berry sorbet over the ginger crumb base, and freeze until firm. Place remaining berry sorbet in a container and freeze until required.
- 3For peach frozen yoghurt, preheat oven to 180C. Combine peaches, 60gm sugar and vanilla in a large bowl, toss to combine, then place peaches cut-side up on a baking tray lined with baking paper and roast, turning once until golden (50-55 minutes). Set aside until cool enough to handle, then peel and process peaches and peach juices in a food processor until smooth. Stir remaining caster sugar and 220ml water in a small saucepan over medium heat to dissolve sugar, then simmer until syrupy (3-4 minutes). Set aside to cool (45 minutes). Combine yoghurt, lemon juice, peach purée and sugar syrup in a bowl, whisk to combine and refrigerate until well chilled (3 hours). Churn in an ice-cream machine until frozen, then spread half on top of the berry sorbet, smooth top and freeze until just firm (1 hour to 1 hour 20 minutes). Freeze remaining peach frozen yoghurt in a container until required.
- 4Remove remaining berry sorbet from the freezer and let sit at room temperature, stirring occasionally, until smooth and soft enough to spread (10-12 minutes). Spread over the frozen-yoghurt layer of cake, smooth top and return to freezer until just frozen (1 hour to 1 hour 20 minutes). Remove remaining peach frozen yoghurt from freezer and let sit at room temperature, stirring occasionally, until smooth and soft enough to spread (10-12 minutes). Spread over sorbet, smooth top and freeze completely (4 hours).
- 5For Italian meringue, stir sugar and 100ml water in a saucepan over medium heat to dissolve sugar, then simmer until syrup reaches 115C on a sugar thermometer. Start whisking eggwhites in an electric mixer until soft peaks form. Continue heating the sugar syrup to 121C, then add to eggwhite in a thin steady stream, whisking until incorporated, and continue whisking until cool (8-10 minutes). Remove ice-cream cake from tin (see note), top with meringue, then toast lightly with a blowtorch (8-10 seconds). Scatter with raspberries and serve.
Note We've used thin Swedish ginger biscuits here, which are available at delicatessens and supermarkets. If you can't find these, substitute another thin ginger biscuit. Powdered glucose is available from health-food stores. If removing cake from tin is difficult, set aside to soften slightly (10-12 minutes), then, once unmoulded, return to freezer for 10-15 minutes. before topping with meringue, or run a hot knife around the inside.