Grease 4 ramekins and sprinkle with caster sugar; shake out any excess sugar. Place into the fridge to chill.

Pre-heat over to 350°F and place a baking sheet into it.

Place the egg whites into a large bowl and egg yolks and caster sugar into a smaller bowl.

In a separate bowl, whisk cream, flour, and corn flour.

Heat milk in a saucepan until just boiling. Add the milk to the cream and flour mixture, adding a little at a time and whisking well. Pour back into the saucepan and beat over a gentle heat until it thickens. Ensure that it does not stick to the sides of the pans. Once thickened, remove from heat and add the lemon zest and juice.

Beat the egg yolk and sugar mix until a thick paste forms. Add this to the cream mixture in the saucepan and return to heat until it begins to bubble. Remove from heat.

Whisk the egg whites until soft peaks form.

Once the saucepan mixture has cooled, add a large spoonful of egg whites and beat well. Transfer the remaining egg white and gently fold them in until the mixture is pale yellow and there is no streaks.

Fill the ramekins and place onto the baking sheet in the oven. Cook for about 14 minutes until they have risen and a re a golden color. Dust with powdered sugar and serve.