Preheat oven to 375 °F (190 °C) and line baking sheets with parchment paper.

In a medium bowl whisk together flour, baking soda, and salt.

In a large bowl, cream together the softened butter and granulated sugar until light and fluffy.

Mix in the egg, vanilla, then peanut butter until smooth.

Gradually stir in the dry ingredients until just combined—avoid overmixing.

Scoop dough (about 1½ tablespoons) onto prepared sheets. Press with a fork in a criss-cross pattern and sprinkle lightly with sugar.

Bake for 12–15 minutes until edges are set but centers slightly soft. After removing, gently tap sheets on countertop to slightly flatten cookies if needed.

Let cookies cool on baking sheet for 10 minutes before transferring to a wire rack to cool completely.