1 cup butter
1/2 cup granulated sugar
1 cup firmly packed light brown sugar
1 cup smooth peanut butter
2 large eggs
2 tablespoons vanilla extract
2 cups quick-cooking rolled oats
2 1/2 cups all-purpose flour
1 teaspoon baking soda
12 ounces semisweet chocolate chips
Preheat oven to 350F. Prepare cookie sheets with silpat or parchment paper.
In the work bowl of your stand mixer on medium speed, cream butter and sugars until smooth. Add peanut butter and mix until combined; then add eggs and vanilla, scraping down sides of bowl as needed.
In another medium bowl, whisk together oats, flour, and baking soda. Add to butter mixture and mix on low until well incorporated. Stir in chocolate chunks by hand.
Drop dough by rounded tablespoons 1 inch apart onto cookie baking sheets. Bake 10 to 12 minutes, until lightly browned but still soft in the center. Transfer cookies to racks to cool.