In a large jug, whisk together the cream, eggs, half of the icing sugar and vanilla extract together.
To make the syrupy plums; in a small saucepan, combine sugar, water and vanilla extract. Stir on low heat until sugar dissolves. Add fruit and bring to the boil on high. Reduce heat to medium and simmer 1-2 minutes, until syrupy. Remove from heat.
To make french toast; melt butter in a frying pan on high, until foaming. Dip each toast slice into egg mixture to coat well. Cook bread for 1 minute each side, or until golden brown. Place on a serving plate.
Spoon fruit and syrup over toast. Dust with icing sugar. Accompany with a dollop of mascarpone.