1. Put half the blueberries in a small saucepan with the sugar and 1 tbsp water. Heat gently, stirring frequently until the blueberry juices start to run. Stir in the remaining blueberries, transfer to a bowl and leave to cool slightly.
2.Stir the lemon curd into the crème fraîche and divide half among 4 small dessert glasses. Spoon half the blueberries on top and add a scoop of vanilla ice cream. Spoon all but a couple of tablespoons of the blueberries on top and then the rest of the lemon curd mixture. Top with the reserved blueberries. Serve immediately.