Peanut Butter Buckeye Brownies

INGREDIENTS:

For the Brownies:

1/3 cup Dutch-processed cocoa
1 1/2 teaspoons instant espresso (optional)
1/2 cup plus 2 tablespoons boiling water
2 ounces unsweetened chocolate, finely chopped
4 tablespoons (1/2 stick) unsalted butter, melted
1/2 cup plus 2 tablespoons vegetable oil
2 large eggs
2 large egg yolks
2 teaspoons vanilla extract
2 1/2 cups (17 1/2 ounces) sugar
1 3/4 cups (8 3/4 ounces) unbleached all-purpose flour
3/4 teaspoon table salt
6 ounces bittersweet chocolate, cut into 1/2-inch pieces
3/4 cup coarsely chopped peanuts

For the Peanut Butter Layer:

1 (14 oz) can sweetened condensed milk)
1/2 cup peanut butter

INSTRUCTIONS:

Preheat oven to 350F. Butter the bottom and sides of a 9×13 inch metal baking pan. Put a long piece of parchment paper in the bottom of the pan, letting the parchment extend up two sides of the pan and overhang slightly on both ends. Place another piece of parchment paper in the same manner, perpendicular to the first sheet. (This will make it easy to remove the bars from the pan after they have baked.) Butter the parchment.
In a large bowl, whisk cocoa, espresso powder, and boiling water together in large bowl until smooth. Add unsweetened chocolate and whisk until chocolate is melted. Whisk in melted butter and oil. Add eggs, yolks, and vanilla and continue to whisk until smooth and homogeneous. Whisk in sugar until fully incorporated. Add flour and salt and mix with rubber spatula until combined. Fold bittersweet chocolate and peanuts.
Spread half of brownie batter into the prepared baking dish.
In a medium bowl combine peanut butter and sweetened condensed milk with whisk. Pour mixture over brownie batter.
Drop the remaining brownie batter in 8 dollops over peanut butter layer in the pan. Swirl in with a knife or spatula.
Bake until toothpick inserted halfway between edge and center comes out with just a few moist crumbs attached, 30 to 35 minutes. Transfer pan to wire rack and cool 1½ hours.
Using parchment overhang, lift brownies from pan. Return brownies to wire rack and let cool completely, about 1 hour.
Cut into 2-inch squares and serve.