Peanut Butter Swirl Brownies

I've had these brownies bookmarked for ages now, but have not made them because my husband doesn't like peanut butter and chocolate together (freak!). So since he was on a diet and I was craving a sweet, I pulled the recipe from the archives and I'm very glad I did! These were fantastic, I loved the peanut butter filling especially. The brownie was good, but was a bit cake like for me personally. Next time I'd omit an egg to make them a bit fudgier. But all in all, these were delicious and absolutely hit the spot!

Ingredients
Source: Martha Stewart

FOR THE BATTER

8 tablespoons (1 stick) unsalted butter, cut into small pieces, plus more for pan
2 ounces good-quality unsweetened chocolate, coarsely chopped
4 ounces good-quality semisweet chocolate, coarsely chopped
2/3 cup all-purpose flour
1/2 teaspoon baking powder
1/4 teaspoon salt
3/4 cup granulated sugar
3 large eggs
2 teaspoons pure vanilla extract

FOR THE FILLING
4 tablespoons unsalted butter, melted
1/2 cup confectioners' sugar
3/4 cup smooth peanut butter
1/4 teaspoon salt
1/2 teaspoon pure vanilla extract

Directions

1. Preheat oven to 325 degrees. Butter an 8-inch square baking pan and line with parchment, allowing a 2-inch overhang. Butter lining (not overhang).
2. Make batter: Put butter and chocolates in a heatproof medium bowl set over a pan of simmering water; stir until melted. Let cool slightly. Whisk together flour, baking powder, and salt in a bowl.
3. Whisk granulated sugar into chocolate mixture. Add eggs, and whisk until mixture is smooth. Stir in vanilla. Add flour mixture; stir until well incorporated.
4. Make filling: Stir together butter, confectioners' sugar, peanut butter, salt, and vanilla in a bowl until smooth.
5. Pour one-third of batter into prepared pan; spread evenly with a rubber spatula. Drop dollops of peanut butter filling (about 1 tablespoon each) on top of batter, spacing about 1 inch apart. Drizzle remaining batter on top, and gently spread to fill pan. Drop dollops of remaining filling on top. Gently swirl peanut butter filling into batter with a butter knife, running the knife lengthwise and crosswise through layers.
6. Bake until a cake tester inserted into brownies (avoid center and edges) comes out with a few crumbs but is not wet, about 45 minutes. Let cool slightly in pan, about 15 minutes. Lift out; let cool completely on a wire rack before cutting into squares. Brownies can be stored in an airtight container at room temperature up to 3 days.