Preheat and prep: Set your oven to 350°F (175°C).
Line a baking sheet with parchment paper.
Mix the wet ingredients: In a medium bowl, whisk the peanut butter, granulated sugar, brown sugar, egg, and vanilla until smooth and glossy.
Combine dry ingredients: In a separate small bowl, stir together the flour, baking soda, and salt.
Bring it together: Add the dry mixture to the wet and fold until just combined. If using, fold in the mini chocolate chips. The dough will be thick.
Portion the dough: Scoop about 1 heaping tablespoon per cookie (around 24–26 grams each).
Roll into balls and space them 2 inches apart on the baking sheet.
Flatten gently: Use your fingers or the bottom of a glass to press each ball to about 1/2 inch thick. For a classic look, make a crisscross pattern with a fork.
Bake: Bake for 8–10 minutes, until the edges look set and the tops are slightly cracked. They should still look soft in the center.
Cool: Let the cookies rest on the sheet for 5 minutes, then move to a rack to cool completely.
They firm up as they cool.