1 cup whole milk
½ cup heavy cream
4 large egg yolks
½ cup granulated sugar
3½ tablespoons cornstarch
2 teaspoons vanilla extract
1 tablespoon unsalted butter
In a mixing bowl, whisk together 1/2 cup milk, egg yolks, 1/4 cup sugar, and cornstarch. Set aside.
In a medium saucepan add remaining milk, cream and sugar. Bring the mixture to a light simmer.
Whisk 1/3 cup of the hot liquid into the yolk mixture and continue to mix to prevent yolks from scrambling.
Pour yolk mixture into the pan with the remaining hot liquid and whisk together over medium-low heat. Continue to cook the pastry cream to allow the mixture to thicken.
Once the mixture is thick enough to coat the back of a spoon, stir in the vanilla and butter and whisk until fully incorporated.
Strain mixture into a bowl sitting over an ice bath and allow to cool completely.
Cover the cooled pastry cream and place it in the refrigerator for at least an hour or until ready to use.
To assemble: Slice doughnuts in half, pipe a small amount of pastry cream on the bottom half of the doughnuts and sandwich the tops back on. Finish with a light dusting of powdered sugar. Serve
Tip: If your pastry cream is not as stiff as you would like it you can fold in a 1 1/2 of whipped cream to the mixture to lighten the mixture and allow it to hold its shape.