1.Have egg whites at room temperature.
2.To make lemon curd; chop butter; place in medium saucepan. Lightly beat eggs in small bowl; strain into pan. Add remaining ingredients; stir over low heat, without boiling, about 10 minutes or until mixture thickly coats the back of a wooden spoon. Transfer curd to medium heatproof bowl. Cover; refrigerate until cold.
3.Preheat oven to 160°C (140°C fan-forced). Grease 24cm closed springform pan; insert base of pan upside down to make cake easier to remove. Line base with baking paper.
4.Spread nuts, in a single layer, on oven tray; roast, uncovered, about 12 minutes or until skins begin to split. Cool. Chop nuts finely.
5.Beat egg whites and ¼ cup of the sugar in small bowl with electric mixer until firm peaks form. Add remaining sugar; beat on high speed about 5 minutes or until sugar is dissolved.
6.Meanwhile, coarsely grate chocolate; fold into meringue mixture with nuts. Spread mixture into pan. Bake about 40 minutes. Cool meringue in pan.
7.Beat cream in small bowl with electric mixer until soft peaks form; fold in curd.
8.Spoon curd mixture onto meringue. Refrigerate several hours or overnight until firm.
9.To make the toffee-dipped blueberries used to decorate the cake: Stir 1 cup white sugar with ½ cup water over medium heat until sugar is dissolved. Bring to the boil; boil, without stirring, until sugar has thickened and turns a caramel colour. Push a wooden toothpick into each blueberry. Remove toffee from heat; allow bubbles to subside. Working with one blueberry at a time, hold berry by the toothpick, dip into the thickened toffee. Hold blueberry above the toffee so that a trail of toffee falls from the berry. Hold upside down until starting to set, then place onto cake. You may need to reheat the toffee if it starts to thicken too much.
10.Top cake with blueberries just before serving.
It is fine to use just the one 300ml carton of cream for this recipe.Note