For the cherry meringues, place the sugar and 150ml/5½fl oz water in a pan and boil until the sugar has dissolved and a syrup forms. Add the cherries to the boiling syrup and poach for 1-2 minutes (depending on how ripe the cherries are), or until soft. Transfer to a bowl to cool.
Preheat the oven to 110C/225F/Gas ¼ and line a baking tray with baking parchment.
In a clean bowl, beat the egg whites with the caster sugar until stiff peaks form when the whisk is removed. Add the icing sugar and continue to beat for 4-6 minutes, or until the mixture is smooth and shiny.
Drain the cherries onto kitchen paper to remove as much syrup as possible. Using a large metal spoon, gently fold the cherries into the meringue mixture. Using another large spoon, scoop out a large spoonful of the meringue and shape into a quenelle (rugby ball shape) and place it onto the lined baking tray. Repeat the process to make three more large meringues. Cook in the oven for two hours.
Once cooked, remove from the oven and allow to cool slightly. Then use a palette knife to remove the meringues from the baking tray. Transfer to a cooling rack to cool completely.
For the cherry compôte, place the cherries, sugar and lemon juice in a large saucepan and cook for 5-6 minutes.
To finish the cherry meringues, place the cream and vanilla seeds in a large bowl and whip until stiff peaks form when the whisk is removed.
Once the meringues have cooled, place some cream on the flat side and sandwich another half meringue on the other side.
Place the sandwiched cherry meringues on a serving plate and serve with the cherry compote.