Instructions

• Make the peanut butter cookie dough: in a large mixing bowl, cream together the 1/4 cup salted butter (softened) and the 1/4 cup granulated sugar and 1/4 cup packed brown sugar until light and combined. (If using unsalted butter, add the 1/8 teaspoon salt called for in the ingredient list.)
• Add the 1/4 cup peanut butter and 1 egg to the creamed mixture and mix until combined.
• Add 1/2 cup plus 2 tablespoons unbleached all-purpose flour, 1/2 teaspoon baking soda, and 1/4 teaspoon baking powder to the bowl and mix until the dough is fully combined. Cover the dough with plastic wrap and set aside while you prepare the brownie batter.
• Preheat the oven to 350°F (175°C). Line a 9x13-inch pan with aluminum foil or parchment paper (leave an overhang for easy removal) and set the prepared pan aside.
• Make the brownie batter: bring the 1/2 cup plus 2 tablespoons water to a boil in a medium saucepan. Once boiling, remove the pan from the heat.
• Off the heat, whisk in the 1/3 cup (1 ounce) cocoa and the 2 ounces chopped unsweetened chocolate until fully melted and smooth.
• Whisk in the 4 tablespoons melted unsalted butter and the 1/2 cup plus 2 tablespoons vegetable oil until combined.
• Whisk in the 2 large eggs and 2 large yolks plus the 2 teaspoons vanilla extract until the mixture is smooth.
• Gently whisk in the 2 1/2 cups sugar until incorporated.
• Add the 1 3/4 cups all-purpose flour and the 1/2 teaspoon salt and gently whisk until just combined; do not overmix.
• Transfer the brownie batter to the prepared 9x13 pan and spread it evenly into the corners.
• Drop scoops or dollops of the reserved peanut butter cookie dough evenly across the surface of the brownie batter.
• Bake in the preheated 350°F oven for 30–40 minutes, or until a toothpick inserted in the center comes clean.
• Remove the pan from the oven and let cool in the pan for at least 10–15 minutes before cutting.
• Cut into 36 brownies by making 5 evenly spaced cuts lengthwise and 5 evenly spaced cuts crosswise to form a 6-by-6 grid.