Preheat the oven to 350?F (175?C).

In a mixing bowl, combine the flour, baking soda, and salt.

In another bowl, beat together the softened butter, peanut butter, brown sugar, and granulated sugar until creamy.

Add the egg and vanilla extract, mixing until well combined.

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

Using a cookie scoop, drop dough onto a baking sheet lined with parchment paper.

Flatten each cookie slightly with a fork, creating a crisscross pattern.

Bake for 10-12 minutes or until the edges are lightly golden.

Remove from the oven and let cool on the baking sheet for a few minutes before transferring to a wire rack.