In a large mixing bowl, combine the egg yolks, sugar, and vanilla paste (or extract). Using a hand whisk or electric mixer, beat the ingredients together until the mixture turns pale, light, and fluffy. Keep whisking until it doubles or even triples in volume—this step ensures a smooth and creamy base for your pastry cream.

Pour the milk into a saucepan and heat it on the stove until it reaches a boil. Alternatively, you can heat it in the microwave. The milk must be extremely hot, as this will help temper the eggs and thicken the mixture later. Be cautious to avoid scalding the milk.

Gradually sift the cornstarch into the egg yolk mixture to prevent lumps. Whisk thoroughly to ensure the cornstarch is fully incorporated and the mixture is smooth.

While continuously whisking the egg mixture, slowly pour in the hot milk. Add the milk gradually to avoid cooking the eggs. You don’t need to add all the milk at once; start with half and whisk until smooth before adding more.

Pour the combined mixture back into the saucepan. Place it over low to medium heat and whisk constantly. Pay attention to the bottom and sides of the pan to prevent scorching.

6- Cook until thickened

Continue stirring and cooking the mixture until it thickens to a creamy consistency. The cream should coat the back of a spoon and hold its shape when stirred. Once thickened, remove it from the heat immediately to prevent overcooking.