Cream butter, shortening, dark brown sugar, and white sugar in a large mixing bowl using a hand mixer or stand mixer.
Beat in eggs and vanilla.
In a medium bowl combine flour, baking soda, baking powder and salt. Stir. Add dry ingredients to wet ingredients and stir until combined.
Stir in oats.
Stir in chocolate chunks and chocolate chips.
Using a medium cookie scoop (2 Tbsp.) scoop cookie dough and stack two cookie dough balls, one on top of the other, on cookie sheets lined with parchment paper. Bake 4-6 cookies per sheet to allow for room to spread. (See photo in blog post for a visual)
Bake cookies for 11-13 minutes. Allow cookies to rest on the baking sheet for 3 minutes before transferring them to a wire rack.
Video
Notes
Cookies are best served warm. Cookies can be reheated in the microwave for 5 seconds. Store cooking in an airtight container.