Prep large cookie sheet with a sheet of parchment and preheat oven to 410 degrees.
In a stand mixer fitted with a paddle attachment, whip up the butter for 1 minute until it's light and fluffy, then add in the sugars to cream together with the butter for 3 minutes on high speed.
Scrape down the sides of the bowl and then add in the vanilla and eggs one at a time, whipping up well between each egg addition. Scrape down the sides of the bowl.
Add in the pumpkin pie spice, flour, cornstarch, baking soda, and salt and slowly mix together by hand or on the very lowest mixer speed until just combined (don't overmix!)
Reserve 1/8 cup of cinnamon chips, then on the lowest speed, add in the oatmeal, pecans, and pumpkin. Mix until just barely combined. Split the dough into 12 balls (baseball-sized) and place 6 on a cookie sheet. Hand-press on the cinnamon chips.
Bake for 7-9 minutes. They should be slightly golden, slightly mounded in the middle, thick/tall, and gooey in the center. Let them cool on the pan for 5 minutes, then carefully transfer the cookies to a cooling rack to finish cooling. Enjoy!