Pastry Cream - (CRÈME PÂTISSIÈRE)

So, you are all pretty familiar with Pastry Cream. Its the filling you enjoy in a chocolate eclair or that savory napoleon. That creamy whipped cream that oozes every time you take a bit. Well, here is the recipe for this delightful cream.
Pastry Cream - Yield about 1 1/8th quart
Ingredients:
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Milk - 1 L
Sugar - 125g
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Egg Yolks - 90g
Whole Eggs - 125g
Cornstarch - 75g
Sugar - 125g
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Butter - 60g
Vanilla Extract - 15mL