Perfect Pastry Cream

Heat milk, vanilla, and about half of the sugar in a pot until it simmers.
14.1 oz Whole Milk, ½ pod Vanilla beans
Mix yolks, the rest of the sugar, and salt in a bowl until it looks pale.
And add flour and mix well.
4 yolks Egg yolk, A pinch Salt, 0.7 oz Cornstarch, 0.7 oz All-purpose flour, 3.5 oz Granulated sugar
Combine the milk and yolk mixture:
Add a small amount of milk first and mix until it gets even.
And add the rest, dividing it into a few more times.
Heat it at medium heat while mixing constantly:
Mix fast, evenly, and constantly to prevent it from getting lumpy and burnt.
When you find it challenging to keep going, try this:
1. Remove it from the heat for a second when it starts getting thick very slightly.
2. Mix fast until it gets smooth.
3. And put it back in the heat to cook more.
After it starts boiling, continue heating while mixing constantly until it gets looser and shinier (Usually another 45 seconds with one batch.)
Remove from the heat and add butter.
1 oz Butter
Strain it.
Emulsify it with a hand blender. (Optional)
Cover the surface with plastic wrap and chill it in the fridge. (1 - 2 hours)
It should look rubbery. Mix well until it looks smooth and shiny.