Roast the plums in advance and allow to cool before assembling and serving.
Preheat the oven to 180C/350F.
Cut the plums in half and place on a small baking tray and sprinkle over the sugar and cinnamon.
Bake for 18 - 20 minutes until starting to release their juices but still firm. Allow to cool completely in the fridge or freezer.
Whip the cream until a medium-firm peaks. Add the icing sugar and vanilla and whisk until combined.
Add the crushed up meringues, and toasted almonds and fold this through the cream mixture.
Cut the plums into small pieces and gently fold them with the juice through the cream and meringue. Reserve one of the plums to slice as garnish for the dessert (or use raw plum slices).
Spoon this mixture into individual serving glasses and garnish with the plum slices and toasted almonds. Serve immediately or set aside in the fridge until you are ready.