First, to make the meringues (do this at least 5 hours ahead) preheat the oven to 120°C fan-forced and line two baking trays with baking paper. In a clean, dry bowl, whisk the egg whites on medium speed until frothy. Gradually add the sugar, one tablespoon at a time, whisking for about 10 seconds between each addition to help it dissolve. 

Once the mixture is glossy and forms stiff peaks, stop the mixer. Add the cornflour and vinegar, then gently whisk on low until just combined. To check the sugar has dissolved, rub a little mixture between your fingers—if it feels gritty, keep whisking.  

Spoon six large meringues onto the trays, spacing them slightly apart. Bake for 80 minutes or until the shells are dry, crisp, and matte. Turn off the oven and allow the meringues to cool completely inside with the door closed. 

While the meringues cook, pit and halve 400g of the cherries and place them in a small saucepan with the caster sugar and ¼ cup water. Bring to a gentle simmer, stirring occasionally to dissolve the sugar. In a separate small bowl, combine the cornflour, lemon juice, and another ¼ cup of water until smooth. Pour this into the simmering cherries and cook, stirring, until the mixture thickens to a glossy sauce. Remove from the heat and let cool completely. 

Whip the thickened cream, vanilla, and icing sugar together until stiff peaks form. Keep chilled until ready to assemble. 

To assemble, place a spoonful of cream onto your serving platter to anchor everything in place. Place a couple of the meringues and layer over the cream, spoonfuls of cherry syrup, chopped pistachios, and whole fresh cherries. Continue layering with meringue, cream, cherry syrup, pistachios and whole cherries, building height and texture as you go. 

Serve at the table alongside a bowl of the remaining whole cherries.