- 4 tablespoons (2 ounces) unsalted butter
- 1/3 cup peanut butter
- 3/4 cup granulated sugar
- 1/4 teaspoon salt
- 1 teaspoon vanilla extract
- 1 1/4 cups all purpose flour
- 4 1/2 ounces unsweetened chocolate, chopped
- 8 tablespoons (4 ounces) unsalted butter
- 1/2 teaspoon salt
- 1/4 cup corn syrup
- 1 cup granulated sugar
- 1 cup all-purpose flour
- 2 large eggs
- 1/2 cup (3 ounces) chocolate chips or peanut butter chips
- 3/4 cup (4 1/2 ounces) white chocolate chips
- 1/4 cup peanut butter
For the crust:
Preheat the oven to 350°F. Line a 9x13-inch baking pan with foil and spray lightly with nonstick cooking spray.
In a medium bowl, use an electric mixer to beat the butter and peanut butter until well combined. Add the sugar, salt, and vanilla and beat until combined. Gradually add the flour, beating until just combined. The mixture will be dry and crumbly.
Press the dough into the prepared baking pan, using a can on its side to help cover the pan evenly with the dough. Bake the crust for 8 to 10 minutes, or until lightly browned at the edges. Keep the oven at 350°F.
For the filling:
In a medium microwave-safe bowl, heat the chocolate, butter, salt, and cornsyrup in the microwave in 30-second bursts until melted and smooth, stirring between each burst. Stir in the sugar and flour. Beat in the eggs until well combined. Stir in the chips. Pour the filling onto the crust and bake until shiny and set, 22 to 24 minutes (a tester will come out with moist crumbs attached). Do not overbake.
For the frosting:
In a small microwave-safe bowl, heat the white chocolate chips in 30-second bursts, stirring between each burst, until melted and smooth. Stir in the peanut butter. Spread the mixture over the warm bars. Let cool completely before cutting into 1 1/2x2-inch bars. For clean cuts, use a sharp knife heated in hot water, wiping often.