Start by separating the egg whites from their yolks, ensuring no yolk gets into the whites. Allow egg whites to sit at room temperature for about 15 minutes, then line baking trays with parchment paper.

Whip egg whites on medium speed until foamy. Gradually add caster sugar, a tablespoon at a time, while continuing to beat on high speed until stiff peaks form and the mixture is glossy. Gently fold in cornflour and vinegar.

Transfer meringue mixture into a piping bag and pipe mounds onto prepared baking trays, creating nests with a slight indentation for filling. Aim for approximately 8-10 mounds.

Preheat oven to 150°C (300°F). Bake meringues at 110°C (230°F) for 1.5 hours until dry and crisp. Turn off oven and leave meringues to cool inside.

Prepare raspberry coulis by simmering fresh raspberries in a saucepan for about 10 minutes, then strain to remove seeds. Prepare lemon curd using egg yolks over a double boiler until thickened, about 10-15 minutes.

In a chilled bowl, beat heavy cream until soft peaks form, careful not to overwhip. Stabilize with gelatin or cornstarch if preparing in advance.

Once meringue shells are cooled, hollow out the center. Fill with raspberry coulis, add lemon curd, and top with whipped cream and optional garnishes.