1Wash the grapes well and remove any stems. Break the eggs and then transfer them to a large mixing bowl. Pour in the caster sugar.
2Beat the eggs and sugar until pale and foamy. Pour in the lukewarm milk and the vanilla extract.
3Stir well again. Sprinkle with the sifted pastry flour and a little pinch of salt and nutmeg.
4Then combine the ingredients in the bowl until you get a silky smooth and runny batter. Butter an 8-inch (20 cm) diameter tart tin and carefully pour the batter in it.
5Top with the grapes.
6Then bake the clafoutis in a preheat the oven to 356°F (180°C) for 40 to 50 minutes until the top is lightly golden and the batter is fully set in the center. The clafoutis will puff up a little while baking but that will disappear while cooling down. Remove the clafoutis from the hot oven and let it cool at room temperature. Then sprinkle with icing sugar and serve lukewarm.