Preheat the oven to 350℉. Line baking sheets with silicone baking mats or parchment paper. Set aside.
In a medium bowl, whisk together the flour, baking soda, baking powder, and salt. Set aside,
2¾ cups all-purpose flour, 1 teaspoon baking soda, ½ teaspoons salt, ½ teaspoon baking powder
Using a hand or stand mixer, cream the butter, shortening, dark brown sugar, and sugar until fluffy.
½ cup unsalted butter, softened, ½ cup shortening, 1½ cups dark brown sugar, packed, ½ cup sugar
Beat in the eggs and vanilla extract until combined.
2 large eggs, 1 tablespoon pure vanilla extract
Add the flour mixture to the wet ingredients, gently mixing until all the flour is combined and no streaks are visible, being careful not to overmix.
Stir in the oats, chocolate chunks, and chocolate chips.
1 cup oats, quick cooking or old-fashioned, 1½ cups semisweet chocolate chunks, ½ cup milk chocolate chips
Using a #40 cookie scoop (2 tablespoons), scoop dough onto prepared cookie sheets. Bake cookies for 11 to 13 minutes. Allow cookies to rest on the baking sheet for 3 or 4 minutes before transferring to a wire rack to cool completely.
Notes
Cookies are delicious served warm. Warm them in the microwave for 5 -7 seconds. Eat carefully, they will be hot.