In a medium mixing bowl, sift flour, baking soda, salt and apple pie spice. Set aside.
In the bowl of a stand mixer, beat butter, dark brown sugar, and granulated sugar. Add eggs, one at a time and mix until fully incorporated. Add vanilla.
With the mixer set to slow, gradually add the flour mixture to the butter/sugar/egg mixture.
With a spoon or a spatula, gently mix in oats and chocolate chips. The mixture will be very thick - be sure to incorporate all of the ingredients!
Scoop large balls of dough onto 2 sheet pans lined with silicone baking mats or parchment paper. Space the cookies at least two inches apart (I usually do 6 cookies per sheet tray to prevent spreading).
Refrigerate dough balls for 30 minutes. Preheat the oven to 350°F.
Bake cookies for 13-15 minutes, until edges are golden brown and the interior is still soft. Cool on the sheet tray for 10 minutes before transferring to a wire cooling rack until the cookies are cooled completely. Enjoy!