For the orange base:
For the egg whites:
For the vanilla sauce:
To make the orange base:
In a small saucepan over low heat mix together the butter and flour and cook for 2 minutes whisking constantly, slowly pour in the milk and sugar and whisk until smooth. Remove from the heat and stir for 1 minute to slightly cool the mixture. Add the remaining ingredients and stir to combine.
To make the egg whites:
In the bowl of an electric mixer fitted with the whisk attachment add the egg whites and cream of tartar and whisk until stiff peaks form, gradually add in the sugar and whip for 2 minutes until glossy.
To make the souffles:
Carefully fold in the whipped egg whites into the orange base, divide evenly amongst the ramekins and bake for 10-15 minutes or until golden brown. Dust with icing sugar and serve with the warm vanilla sauce.
To make the vanilla sauce:
In a bowl combine the egg yolks, flour and sugar and whisk for 2-3 minutes or until pale and creamy. In a small saucepan bring the milk, cream and vanilla to the boil. Gradually add this to the egg yolk mixture whilst whisking constantly, return to the pot and stir over low heat until the mixture coats the back of a spoon.