Line a baking sheet with parchment paper and set aside.
In the bowl of a stand mixer, combine butter, brown sugar, white sugar, egg, and vanilla extract and beat until smooth.
Add flour, rolled oats, baking soda, and salt and beat again until combined.
Fold in chocolate chips, cornflakes, coconut flakes, and pecans and use a cookie scoop to scoop dough onto the prepared baking sheet.
Loosely cover with cling wrap and chill in the fridge for at least 2 hours.
When ready to bake, preheat oven to 350F and bake for 10-12 minutes.
Let cookies cool slightly on the baking sheet.
ENJOY!