Custard cream (Anna Olson)

Ingredients:

1) 1 cup 2% milk
2) 1 teaspoon vanilla extract or vanilla bean paste
3) 1 teaspoon finely grated orange zest
4) 3 large egg yolks
5) 1/4 cup sugar
6) 3 tablespoons cornstarch
7) 2 tablespoons unsalted butter, room temperature

Methods:

1) Mix milk  (but reserve 2 tsp of it aside first), vanilla, and orange zest under medium heat til simmering
2) Whisk egg yolks, sugar, cornstarch, and the 2 tsp of milk in bowl
3) Pour the hot milk mix into the yolks mix while whisking then pour everything back to pot to boil under medium heat til thickens (5 minutes)
4) Put the butter in a mixing bowl and strain the hot custard mix into the bowl 
5) Stir til butter melts
6) Cover with cling films til the film directly touches the surface of the custard
7) Chill for 2 hours at least