Preheat the oven to 100°C fan-forced (120°C conventional). Grease two large oven trays and mark four 4.5cm circles on baking paper as guides.

Beat the egg whites until soft peaks form. Gradually add caster sugar, beating well after each addition until dissolved. Add vinegar and cornflour, then beat until glossy and well combined.

Spoon a quarter of the mixture into a piping bag fitted with a 1cm plain nozzle. Pipe small mounds of meringue using the circles as guides. Fill another piping bag with the remaining meringue fitted with a 0.5cm fluted nozzle and pipe three rows around each mound to create tree shapes.

Bake for 50 minutes to 1 hour until the edges are crisp but not colored. Turn off the oven and leave the meringues inside to cool with the door slightly ajar.

Pulse the pistachios in a small food processor until finely crumbed.

Beat the thickened cream with icing sugar and rosewater until just firm peaks form. Pipe small rounds of cream onto the meringue trees to help the garnishes stick. Decorate with silver cachous, raspberries, and freeze-dried raspberry powder. Sprinkle pistachio crumbs over the top and serve alongside fresh strawberries and the remaining whipped cream.