Preheat oven to 375°F. Line a baking sheet with parchment paper.
In a large bowl, cream together the butter & shortening. Add sugar, eggs, and vanilla and mix until smooth.
Combine the flour, baking soda, baking powder and salt; stir into the sugar mixture.
Stir in the oats and 2 cups chocolate chips just until incorporated.
Drop by rounded scoops onto cookie sheets. Top each cookie with 3-4 additional chocolate chips.
Bake 8-10 minutes until edges begin to brown. Cookies appear fairly light in color even when fully baked! Remove from the oven and let cool on the cookie sheet for 5 minutes before transferring to a cooling rack.
To Make JUMBO Cookies
Pile 2 medium scoops of cookie dough on top of each other and space so that just 6 cookies are on each tray. Again, add additional chocolate chips to the tops of the cookies. Bake 12-14 minutes. Remove from the oven and let cool on the cookie sheet for 5 minutes before transferring to a cooling rack.