In a mixing bowl, beat together 1 cup of creamy peanut butter, 1/2 cup of softened melted butter, and 1 cup of brown sugar until light and fluffy, about 2-3 minutes. Then incorporate 1 egg and 2 teaspoons of vanilla extract until well combined.

In a separate bowl, whisk together 1 ½ cups of all-purpose flour, 1 teaspoon of baking soda, and ½ teaspoon of salt, then gradually add to the peanut butter mixture until just combined.

In another bowl, whisk together 1/2 cup of melted butter and 1 cup of white sugar until smooth, approximately 1-2 minutes.

Next, mix in 1/3 cup of cocoa powder, 1 egg, and another teaspoon of vanilla extract, ensuring everything is well blended.

Carefully fold in 1 cup of flour, 1/4 teaspoon of baking powder, 1/4 teaspoon of salt, and 1 cup of chocolate chips until combined, creating a rich brownie batter.

Cover both the peanut butter and brownie doughs with plastic wrap, and refrigerate them for 30 minutes.

After chilling, scoop 1-2 tablespoons of each dough onto a parchment-lined baking sheet, ensuring at least 2 inches of space between them.

To achieve the signature swirl, gently use a toothpick to swirl the peanut butter dough into the brownie dough.

Place the baking sheet in the preheated oven, and bake for 9-11 minutes.

Once baked, remove the cookies from the oven and let them cool on the baking sheet for 5-10 minutes.

Afterward, use a spatula to move them to a wire rack to cool completely.