Recipe: Judy Rosenberg's Boston Cream Pie Cookies (custard filling and chocolate glaze)

JUDY ROSENBERG'S BOSTON CREAM PIE COOKIES

FOR THE CUSTARD:
1 cup milk, divided use
6 tablespoons heavy (whipping) cream
6 tablespoons sugar
3 tablespoons cornstarch
1/4 teaspoon salt
1 large egg yolk
2 teaspoons vanilla extract

FOR THE COOKIES:
1 cup flour
1 cup plus 2 tablespoons cake flour
3/4 teaspoon baking soda
1/2 teaspoon salt
9 tablespoons unsalted butter at room temperature
1 cup plus 1 tablespoon sugar
2 teaspoons vanilla extract
1/2 teaspoon grated lemon zest
2 large egg yolks at room temperature
1 whole egg at room temperature
1/2 cup plus 2 tablespoons buttermilk at room temperature
Chocolate Glaze (recipe follows)

TO MAKE THE CUSTARD:
Place 1/2 cup plus 2 tablespoons of the milk, the cream, and the sugar in a medium saucepan over medium heat. Bring just to a boil.

Dissolve the cornstarch and salt in the remaining milk in a small bowl. Whisk in the egg yolk and then whisk into the hot-cream mixture. Whisk over medium-low heat until thick, about 2 to 3 minutes. Remove from the heat and stir in the vanilla. Transfer to a bowl, cover the surface with plastic wrap, and refrigerate for 2 to 3 hours.

TO MAKE THE COOKIES:
Preheat the oven to 400 degrees F. Lightly spray several baking sheets with nonstick cooking spray.

Whisk together the flours, baking soda, and salt in a small bowl.

In a medium bowl, beat the butter, sugar, vanilla, and lemon zest until light and fluffy, about 2 minutes. Beat in the egg yolks and then the whole egg, followed by the buttermilk.

Fold in the flour mixture and stir until smooth. Drop by generous tablespoons about 2 inches apart on the prepared sheets.

Bake for 10 to 11 minutes, or until the cookies are firm yet spongy to the touch. Let cool.

TO FILL:
Turn a cooled cookie upside down and spread with a rounded tablespoon of cooled custard. Top with a cookie. Continue in this manner until there are no more cookies.

Spread a scant tablespoon of chocolate evenly across the top of each custard-filled cookie. Serve at room temperature.

CHOCOLATE GLAZE

1/2 cup heavy (whipping) cream
2 ounces unsweetened chocolate, chopped
1 tablespoon plus 1 teaspoon unsalted butter at room temperature
6 tablespoons confectioners' sugar

Scald the cream in a small saucepan. Transfer to a small bowl and add the chocolate and butter. Whisk until smooth. Add the confectioners' sugar and stir until velvety.

Makes 13 cream-filled cookies
Source: Rosie's Bakery Chocolate-Packed, Jam-Filled, Butter-Rich, No-Holds-Barred Cookie Book by Judy Rosenberg