Ingredients
BUTTERCREAM
3/4 cup whole milk
4 large egg yolks
1/3 cup (2 1/3 ounces) sugar
1 1/2 teaspoons cornstarch
1/4 teaspoon salt
2 tablespoons amaretto or water
1 1/2 tablespoons instant espresso powder
16 tablespoons unsalted butter, softened
Preparation
Heat milk in small saucepan over medium heat until just simmering. Meanwhile, whisk yolks, sugar, cornstarch, and salt in bowl until smooth. Remove milk from heat and, whisking constantly, add half of milk to yolk mixture to temper. Whisking constantly, return tempered yolk mixture to remaining milk in saucepan. Return saucepan to medium heat and cook, whisking constantly, until mixture is bubbling and thickens to consistency of warm pudding, 3 to 5 minutes. Transfer pastry cream to bowl. Cover and refrigerate until set, at least 2 hours or up to 24 hours. Before using, warm gently to room temperature in microwave at 50 percent power, stirring every 10 seconds.
Stir together amaretto and espresso powder; set aside. Using stand mixer fitted with paddle, beat butter at medium speed until smooth and light, 3 to 4 minutes. Add pastry cream in 3 batches, beating for 30 seconds after each addition. Add amaretto mixture and continue to beat until light and fluffy, about 5 minutes longer, scraping down bowl thoroughly halfway through mixing.
