Hot plum batter
Preheat the oven to 220°C/ 425°F/Gas mark 7. Lightly oil a wide shallow ovenproof dish with vegetable oil, and add the plums.
Put the milk, milk powder, sugar, vanilla essence, flour and egg whites in a food processor. Whiz until smooth.
Pour the batter over the plums. Bake for 25–30 minutes until well risen and golden. Lightly dust with icing sugar, and serve immediately.