Preheat your oven to 350°F (175°C). This step is crucial for achieving the perfect cookie texture.
In a large mixing bowl, combine the softened butter and the creamy peanut butter. Use your electric mixer to beat them together until smooth and creamy. Gradually add in the packed brown sugar and granulated sugar, mixing until the mixture is light and fluffy.
Add the eggs one at a time, mixing well after each addition. Then, stir in the vanilla extract until fully incorporated.
In a separate bowl, whisk together the all-purpose flour, baking soda, and salt. Gradually add the dry ingredients to the wet mixture, mixing on low speed just until combined. Be careful not to overmix!
If you’re adding any mix-ins, like Reese’s Pieces, chocolate chips, peanut butter chips, or chopped peanuts, now’s the time! Gently fold them into the dough with a spatula.
Using a cookie scoop or tablespoon, drop rounded balls of dough onto your prepared baking sheets, spacing them about 2 inches apart.
Bake in the preheated oven for about 10-12 minutes, or until the edges are lightly golden. The centers may look slightly underbaked, but they will continue to firm up as they cool.
Once baked, remove the cookies from the oven and let them cool on the baking sheet for about 5 minutes. Then, transfer them to a cooling rack to cool completely.