separate 2 egg whites into a container and the yolks into the pot
add the remaining egg, 110g sugar, 40g corn starch and kosher salt and vanilla bean paste to the pot
whisk together until very smooth and the mixture has slightly lightened
add the milk and mix until incorporated
Put it over medium heat and whisk continuously until the mixture thickens, happens around 150–160°F. It should take around 6–8 minutes, so adjust your heat to that
Once it's thickened, remove from heat
Whisk in the butter, stirring continously until it's completely emulsified in
Then add the vanilla extract
Prepare a 1⁄4 sheet pan with plastic wrap, and spread the pastry cream out onto it
Cover with plastic wrap
Refrigerate
Notes
All the extra steps in older recipes are not needed, this works perfectly.
Adding in ~2 tsp of mortar-ground loose-leaf earl grey tea has worked well for me.