Combine the flour, baking soda, baking powder and salt in a medium-sized bowl and set aside.
Cream the butter, peanut butter and sugars together in a large mixer bowl on medium speed until light in color and fluffy, about 2-3 minutes. You should be able to see the change in color happen and know it’s ready.
Add the egg and vanilla extract and mix until well combined.
Add the dry ingredients and mix until the dough is just well combined. Do not over-mix.
Wrap and refrigerate the cookie dough for at least one hour. The cookies turn out even better (thicker and more chewy – and for longer) if you refrigerate it overnight.
After refrigerating the dough, preheat the oven to 350°F and prepare a cookie sheet with parchment paper or a silicone baking mat.
Let the cookie dough soften enough to work with it, then form balls of 1.5 tablespoons (27g) of cookie dough. Use a long pronged fork to press down and flatten the cookies, then turn the fork 90 degrees and press down once more to create the criss-cross pattern.
Bake cookies for 7-10 minutes, or until cookies just start to look cooked in the center and the edges are just barely starting to brown.
Let cool for 3-5 minutes, then move to a cooling rack to cool completely.
Notes
These cookies are best enjoyed fresh, but can be stored in an airtight container at room temperature for up to 3 days.