Mix the flour, baking soda, and salt in a small bowl. Set aside
In the bowl of a stand mixer, using the paddle attachment, beat the peanut butter, butter, egg, sugars, vanilla on medium-high speed until light and fluffy, about 3 minutes. Stop and scrape down the sides of the bowl when necessary. A hand whisk can also be used to do this.
Add the dry ingredients and beat on low speed until just combined—about 1 minute.
Refrigerate the batter for at least 30 minutes. The longer, the better— just for the dough to be slightly firmer, so it can be easier to work with.
Divide the dough into 12 equal balls, then place them on a baking sheet spacing them evenly, flatten slightly with your fingers, and put them in the oven.
Bake the cookies at 350°F for 10 to 12 minutes or until edges have set—the cookies will spread somewhat during baking and may look underdone. Don’t be tempted to overbake them. Leave them to cool on the baking sheet for about 10 minutes. The cookies will firm up as they cool.
Notes
The dough can be prepared up to 5 days early and stored in the refrigerator. When you are ready to use, simply bring it out from the fridge and leave for about 20 minutes before using it.
If you like a soft and chewier cookie texture, bake for the recommended time or about a minute less.
Feel free to add a minute or two to the baking time if you like your cookie a little more crunchy.
Cool the cookies completely before storing in an airtight container for better shelf life.
The best peanut butter for this recipe is the regular store-bought peanut butter. The one that separates with oil on top will not yield the desired result.
Do not bake the cookies without chilling the dough because the unchilled dough is quite soft, and this will cause the cookies to spread out too flat during the baking process.