Preheat your oven to 350°F and prepare a baking sheet with parchment paper.

In a separate bowl, combine the flour, baking soda, and salt, mixing them well before setting aside.

In a large mixing bowl, beat the softened butter along with both sugars until the mixture is light and fluffy, about 2-3 minutes.

Incorporate the egg and vanilla extract, blending until fully integrated.

Gradually fold in the flour mixture, stirring just until combined.

Gently warm the peanut butter in the microwave for about 20 seconds until it becomes slightly runny.

Mix in the chocolate chips until evenly distributed.

Using a tablespoon, drop rounded portions of the cookie dough onto the prepared baking sheet, ensuring they are spaced about 2 inches apart.

To create a marbled effect, use a toothpick to swirl the warmed peanut butter into the cookie dough.

Bake in the preheated oven for 10-12 minutes, or until the cookies are golden around the edges.

Allow them to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.