Preheat your oven to 350°F (175°C) and line your baking sheets with parchment paper.
Cream together the softened unsalted butter and light brown sugar until smooth and fluffy. Beat in the egg, vanilla extract, and creamy peanut butter until fully combined.
Gradually add in the all-purpose flour and baking soda, mixing until just incorporated.
Scoop out about 1-2 tablespoons of dough and roll into balls. Optionally, roll in granulated sugar before placing on the baking sheet.
Use a fork to press down on each cookie ball to create a criss-cross pattern on top, if desired.
Bake for about 7-8 minutes or until lightly golden around the edges. Allow to cool on the baking sheet for 5 minutes before transferring to a wire rack.