Preheat the oven to 350°F (175°C) and line two baking sheets with parchment paper.

In a mixing bowl, combine softened butter, peanut butter, brown sugar, and granulated sugar. Use an electric mixer on medium speed to cream for 2–3 minutes until fluffy.

Add one egg and vanilla extract to the mixture. Mix on low speed until fully combined, about 30 seconds.

Gradually stir in the flour and baking soda until the dough comes together. Do not overmix.

Scoop the dough, roll it into balls, and optionally roll each ball in granulated sugar. Place on baking sheets and press down with a fork.

Bake for 9–11 minutes until the edges are set and the centers are slightly soft. Remove from oven and let cool on sheets for 5 minutes.

Transfer cookies to a wire rack to cool completely before enjoying.