Now that the weather is warming up, it's a great choice for dessert. Be aware that it does involve raw egg white, so, if you have a problem with that, you have two choices: you can either give the recipe a miss altogether, or you can leave out the egg whites, which will result in a heavier mixture more like an 'instant pudding' than a mousse.
Just in case you don't do so as a matter of course, I suggest preparing all the ingredients before you start and have them readily to hand, because there is a point at which you need to work quite quickly, and to still have to measure out ingredients at that stage will slow you down.
175g demerara sugar
2 egg whites
- Blend a little milk with the cornflour in a saucepan to make a smooth paste. The saucepan should be large enough to hold all the contents eventually.
- Add the rest of the milk and stir over a gentle heat until it thickens. Keep stirring until it comes to the boil, signified by large, glooping bubbles rising up. What you have now is more or less a white sauce. Set it aside, but not too far away.
- In another saucepan, completely melt the sugar over a medium heat.
- Now you need to work quite quickly. Stir in the butter until it has completely melted.
- Still working quickly (before the sugar mixture sets into toffee), stir the sugar/butter mixture into the white sauce. If the sugar toffee-fies itself before you've added all of it to the white sauce, you could gently heat it again, to re-liquify it and then stir it in. Don't worry too much if there are small lumps of toffee in the mixture at this point, we're about to deal with that.
- Strain the mixture to get rid of lumps and clumps and to result in a completely smooth texture.
- Stir in the vanilla and set aside while you attend to the egg whites.