Separate your egg yolks from the egg whites. In a medium bowl, whisk your egg yolks together. Add in 2 tbsp. of sugar and continue to whisk together. Once sugar has dissolved, whisk in the cornstarch and continue to whisk until the mixture is thick and pale yellow.
In a medium saucepan on the stove, add your heavy cream, salt, and the rest of your sugar. Stir until your sugar has dissolved.
When the cream has reached a low simmer, whisk it into the egg yolk mixture. Mix together well and put the mixture back into the saucepan on a low heat. Whisk constantly until a few bubbles begin to emerge onto the surface and the mixture is creamy and glossy.
Remove from the heat and whisk in the butter and vanilla.
Strain through a fine mesh sieve.
In a medium bowl put your pastry cream, and place cling film nice and tight across the cream.
Place in the fridge for at least 3 hours before use and up to 3 days.