- Yield:makes 4 dozen 1 1/2-inch-square bars
- Active time: 1 hour
- Total time:3 hours
- For the peanut shortbread crust:
- 7 ounces (14 tablespoons) unsalted butter, melted and cooled to just warm
- 1/2 cup granulated sugar
- 1/2 teaspoon table salt
- 9 1/2 ounces (2 cups plus 2 tablespoons) unbleached all-purpose flour
- 1/2 cup unsalted peanuts, finely chopped
- For the peanut butter filling:
- 1 cup creamy peanut butter (not natural but an emulsified variety such as Jif)
- 3 ounces (6 tablespoons) unsalted butter, at room temperature
- 6 ounces (1 1/2 cups) confectioners’ sugar
- 1 teaspoon pure vanilla extract
- For the ganache:
- 5 ounces good-quality bittersweet chocolate, such as Lindt Excellence, chopped (about 1 heaping cup)
- 1/2 cup plus 2 tablespoons heavy cream
Make the peanut shortbread: Line a straight-sided 13x9-inch metal baking pan with foil, letting the ends create an overhanging edge for easy removal.
In a medium bowl, stir the butter, sugar, and salt. Stir in the flour and peanuts to make a stiff dough. Press the mixture evenly into the bottom of the prepared pan. Prick the dough all over with a fork. Refrigerate the pan for 30 minutes (or freeze for 5 to 7 minutes), until the dough is firm.
Meanwhile, position a rack in the center of the oven and heat the oven to 325°F.
Bake the dough for 20 minutes, then reduce the oven temperature to 300°F and bake until the crust is golden-brown all over and completely set, 20 to 25 more minutes. Let the crust cool completely before topping.
Make the peanut butter filling: Put the peanut butter and butter in the bowl of a stand mixer fitted with the paddle attachment (or in a large bowl for hand mixing) and beat on medium speed until smooth, about 1 minute. Add about half of the confectioners’ sugar to the mixer along with the vanilla and 1 Tbs. hot water. Beat on low speed until combined, then on medium speed until smooth and fluffy, about1 more minute. Beat in the remaining sugar and mix, about 1 more minute, until the mixture is smooth and thick, like frosting. If the filling seems too stiff, add another 1 Tbs. hot water and beat for another minute.
With a knife or metal offset spatula, spread the filling over the fully cooled crust. The filling may not spread smoothly and evenly, but don’t worry; the ganache will cover it.
Make the ganache: Put the chocolate in a small heatproof bowl. In a small saucepan, bring the heavy cream to a boil. Remove from the heat and pour over the chocolate. Let sit for 3 minutes. Stir gently with a rubber spatula until combined and smooth.
Spread the ganache over the peanut butter filling with a metal offset spatula to coat evenly. Let the bar sit for at least 3 hours to allow the ganache to set before cutting (or refrigerate for 1 hour).
Carefully lift the bar from the pan using the foil sides and transfer them to a cutting board. Separate the foil from the bar by sliding a spatula between them. Cut into 1 1/2-inch-square bars. They will keep at room temperature for 1 week.