This super-chocolatey treats are perfect for a cookie buffet.
Preheat oven to 350 degrees. Whisk together flour, oats, baking powder, baking soda, and salt in a medium bowl; set aside.
Put butter and sugars in the bowl of an electric mixer. Mix on medium speed until smooth, about 3 minutes. Mix in egg and yolk. Reduce speed to low; slowly mix in flour mixture until smooth. Mix in all chocolate chunks and the pecans.
Scoop dough into balls using a 1 1/2-inch ice-cream scoop. Space 2 inches apart on parchment-lined baking sheets.
Bake until edges turn golden, about 12 minutes. Let cool on sheets 2 minutes. Transfer to wire racks to cool completely.