Prepare a baking tray lined with greaseproof paper.
Drain the chickpeas in a colander, reserving the chickpea water (aquafaba) in a large bowl. Add the white vinegar.
Use an electric whisk on its highest setting to whisk the aqaufaba until it forms soft peaks; this should take approximately 10 minutes.
Add the caster sugar 1 tbsp at a time, whisking well in between each addition. The meringue should form firm peaks after 7 minutes. Whisk in the vanilla extract.
Stain the raspberries in a seive. Pour the juice around the circumference of a piping bag, ensuring it doesn’t collect at the nozzle. Scoop the meringue into the piping bag until two-thirds full.
Pipe 20 meringue nests onto the baking tray, leave a 1 inch space between each nest.
Bake at 90°C fan for 1hour 10mins. Turn off the oven and leave the meringue nests to cool, with the oven door open, for 45 minutes.
Meanwhile make a start on the plum compote. Slice the plums and place in a saucepan with the remaining ingredients. Bring to the boil, then reduce the heat and simmer for 10 minutes, mashing the plums as they soften. Pour the compote into a bowl and chill in the fridge for 45 minutes.
To prepare the Eton mess, pour half the compote into 4 serving glasses. Roughly mash the meringue nests and layer these over the compote. Follow with 1/2 the cream. Repeat these steps finishing with the meringue nests, slices of fresh plums and a sprinkling of demerara sugar.