Step 1
Lightly spray a 24cm springform pan, with at least 6cm high sides, with non-stick cooking spray.
Step 2
In a medium saucepan over medium heat, bring 300g of the raspberries, ⅔ cup (150g) of the sugar, lemon juice and vanilla to a simmer. Simmer, stirring frequently, for 18 mins or until mixture thickens. Transfer the raspberry mixture to a shallow container. Cover and refrigerate until cold.
Step 3
Meanwhile, in a small bowl over a saucepan of simmering water, stir 80g of the chocolate and the butter until melted and blended. In a food processor, process the biscuits into very fine crumbs. Add the chocolate mixture and a pinch of salt and pulse until moistened. Press crumb mixture evenly onto the base and 4cm up the side of prepared pan. Freeze for 10 mins to harden crust.
Step 4
Spread half the ice-cream over crust to cover the base. Spoon the raspberry mixture over ice-cream. Sprinkle half the remaining chocolate over the raspberry mixture. Top with remaining ice-cream and chocolate. Using a butter knife, swirl ice-cream and raspberry mixture to create a marbled look. Smooth the top. Cover and freeze for at least 8 hours or until firm.
Step 5
Carefully run a knife between the crust and the side of the pan to loosen, then remove ice-cream cake from pan and transfer to a serving platter. Return to freezer while you make the meringue.
Step 6
In a medium bowl over a saucepan of simmering water, using an electric hand mixer, beat egg whites and remaining sugar constantly for 3 mins or until mixture is frothy and sugar granules have dissolved (take care with electrical cord near stove). Remove bowl from heat and continue beating for 4 mins or until meringue holds stiff, glossy peaks. Using a large spoon, transfer meringue onto the cake and spread decoratively.
Step 7
Using a kitchen blowtorch, brown the meringue to caramelise. Decorate cake with remaining raspberries and serve immediately.