Preheat oven to 350℉. Line two or three baking sheets with parchment paper or reusable silicone baking mat. Set aside.
In the bowl of a stand mixer, cream together butter, brown sugar, sugar, and vanilla until well combined. Add peanut butter and mix on medium speed until creamy. Scrape down sides of bowl as needed to ensure thorough mixing.
Add eggs one at a time. Mix on low until well combined.
In a food processor or blender, process 1 cup (95 g) of rolled oats until finely ground. Mix with baking powder, baking soda, cinnamon, and salt. Add dry mixture to mixing bowl. Mix until incorporated.
Fold in remaining 2 cups (190 g) rolled oats, chopped pecans, and chopped chocolate until evenly distributed among cookie dough.
Use a size 24 scoop to portion out dough. Place rounded mounds of cookie dough on prepared baking sheet, spacing each about 2-inches apart. Bake for 12-15 minutes until lightly golden brown around the edges. Rotate pans midway through baking. Cookies will spread during baking. If fresh baked cookies are not circular in shape, use a spatula or mini offset to gently reshape the cookies. Let cool in baking sheet for about 5-8 minutes before transferring to wire rack.