Step 1: Prepare the Peanut Butter Dough

1. In a large mixing bowl, cream the peanut butter, softened butter, and brown sugar until the mixture is smooth and creamy.
2. Add the egg and vanilla extract, mixing until fully incorporated.
3. In a separate bowl, whisk together the flour, baking soda, and salt.
4. Gradually combine the dry ingredients with the wet mixture, stirring until a soft dough forms. Cover the dough and set it aside.

Step 2: Prepare the Brownie Dough

1. In another mixing bowl, whisk the melted butter and sugar until smooth.
2. Stir in the cocoa powder, then add the egg and vanilla extract, mixing well.
3. In a separate bowl, mix the flour, baking powder, and salt.
4. Slowly incorporate the dry ingredients into the wet mixture until the dough is thick and cohesive.
5. Gently fold in the chocolate chips for a rich, chocolatey finish.

Step 3: Form the Swirled Cookies

1. Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.
2. Scoop a small amount of peanut butter dough and a small amount of brownie dough. Gently press them together to form a swirled ball.
3. Roll the combined dough into a ball, keeping the swirls distinct.
4. Place the dough balls on the prepared baking sheets, leaving about 2 inches between each. Flatten the cookies slightly with your hand.

Step 4: Bake the Cookies

1. Bake the cookies for 10–12 minutes, or until the edges are firm. The centers should still appear soft.
2. Let the cookies rest on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.