Preheat oven to 350°F. Line cookie sheets with parchment paper or silicone baking mats.
Cream together butter and sugars until light and fluffy, about 3 minutes. Add in eggs and vanilla and mix until combined.
In a medium bowl, whisk together the flour, oats, baking soda, cinnamon and salt. Slowly add the flour mixture to the wet ingredients. Just before combined, stir in chocolate chips and mix until incorporated.
Use a large cookie scoop (3 tablespoons) to portion dough onto prepared cookie sheets. Bake for 14 minutes or until golden brown. Allow to sit on cookie sheets for about 2 minutes before removing them to a wire rack to cool completely. Repeat with remaining dough.
Notes
Makes about 22 large cookies or 44 small cookies.
To make small cookies, use a 1 1/2 tablespoon (medium) cookie scoop and bake for 10-11 minutes.
Bake 1 sheet at a time for best results. If baking 2 sheets at once, rotate pans halfway through baking.