Preheat your oven to 350°F (175°C) and gather your tools: mixing bowl, whisk, and baking sheet lined with parchment paper.

In a medium bowl, whisk together the flour, cocoa powder, baking soda, and salt until well combined.

In a large mixing bowl, beat together softened butter, granulated sugar, and brown sugar until light and fluffy, about 2-3 minutes.

Mix in the egg and vanilla extract until fully incorporated.

Gradually add the dry ingredients to the butter mixture, stirring gently until just combined.

Warm the creamy peanut butter slightly in the microwave for about 15-20 seconds.

Drop spoonfuls of warmed peanut butter into the cookie dough and gently swirl it using a spatula.

Using an ice cream scoop, portion the cookie dough onto the prepared baking sheet, spacing them 2 inches apart.

Bake for approximately 10 minutes, or until the edges are set and centers look slightly soft.

Allow cookies to cool on the baking sheet for about 5 minutes, then transfer to a wire rack to cool completely.