Preheat Oven: Set your oven to 350°F (175°C). Line a baking sheet with parchment paper.
Mix Wet Ingredients: In a large bowl, beat peanut butter, granulated sugar, and brown sugar together until creamy. Add the egg and vanilla extract, mixing until well combined.
Add Dry Ingredients: Stir in baking soda, salt, and flour until a soft dough forms. If using add-ins, fold them in at this stage.
Shape the Cookies: Scoop about 1 tablespoon of dough and roll it into a ball. Place on the baking sheet about 2 inches apart.
Create the Classic Peanut Butter Pattern: Use a fork to press down each dough ball, creating a crisscross pattern.
Bake: Bake for 10–12 minutes until the edges are lightly golden. The cookies may look soft but will firm up as they cool.
Cool & Serve: Let the cookies rest on the baking sheet for 5 minutes before transferring them to a cooling rack. Enjoy!