Preheat oven to 325 degrees. Line two light-colored baking sheets with parchment paper and set aside.
In a large bowl, cream butter, peanut butter, brown sugar and granulated sugar together until light and fluffy, about 3-4 minutes. Stir in eggs and vanilla until well combined.
Slowly incorporate remaining ingredients until the dough has just come together.
Scoop into cookies and place on prepared sheets. Bake 9-12 minutes or until edges are golden brown and the centers are soft but not gooey.
Cool 5 minutes on the hot baking sheet before transferring to cooling racks. Store in airtight containers for up to 3 days.
Notes
I use and prefer salted butter for all my baking. However, if you prefer unsalted butter, increase the salt to 1 teaspoon.