2tablespooncornstarchalso known as cornflour in the UK
In a medium bowl whisk together the sugar, cornstarch, egg and yolks. Set aside.
In a medium saucepan, heat the milk and vanilla over a medium high heat until simmering.
Allow the milk to simmer for a minute or two while stirring before tempering your eggs. To temper - slowly and steadily pour the the milk into your egg mixture whilst whisking the egg mixture to incorporate. Once all the milk has been whisked into the eggs, pour the whole mixture back into your saucepan.
Return the saucepan to your stovetop and continue heating on medium high heat whilst whisking continuously until thickened (about five minutes). Once thick, pour into a clean bowl and cover the surface with cling film to prevent a skin forming. Place in your fridge to chill for about 2 hours (or up to three days).
When ready to use, remove the cling film and give the pastry cream a good stir!