Note: This makes enough pastry cream to fill roughly 6 eclairs in the attached recipe.
3 tablespoons butter, cut into ½-inch pieces
2 1/2 cups half-and-half
1/2 cup sugar
1/4 teaspoon salt
1 (4-inch) piece split vanilla bean
2 egg yolks
1/4 cup cornstarch
1. Place the butter in a strainer set over a medium bowl. Place the bowl over a larger bowl of ice water to form an ice bath.
2. In a medium, heavy-bottomed saucepan heated over medium-high heat, whisk together the half-and-half, sugar, salt and vanilla bean. Cook, striring frequently, until the mixture comes to a boil, 5 to 7minutes.
3. Meanwhile, in a large bowl, whisk together the eggs, egg yolks and cornstarch.
4. Whisk one-half cup of the boiling half-and-half into the egg mixture to temper the eggs, then slowly stir the egg mixture into the hot liquid. Increase the heat to high and cook, stirring frequently (and scraping all sides and the bottom of the pan), until the mixture thickens and comes to a boil.
5. Immediately remove the pan from heat and pour the mixture over the butter in the strainer. Strain the pastry cream, then gently stir until the butter is completely incorporated.
6. Place a sheet of plastic wrap over the surface of the cream to prevent a skin from forming, and set aside until cooled. Use immediately, or refrigerate until needed.