Yoghurt-pot cake (Nigella's breakfast chambella)

• 3 eggs separated
• 1 pot of yoghurt
• 2 pots sugar
• 1 pot of oil
• 1 pot cornflower
• 1/2 lemon 's worth of lemon zest
• 2 caps of vanilla

1. Whisk white until stiff and set aside
2. To egg whites add the yoghurt and 2 yoghurt pots full of sugar and whisk add oil and cornflower while whisking
3. Mix in lemon and vanilla. Fold in 1/3 of egg white vigorously then gently fold in the remaining 2/3
4. Pour into ring tin (fill almost to the rim)
5. 1.2 hour in moderate oven and once cooled dredge in icing sugar and serve