Preheat the oven to 350℉/176℃ and line 2 baking trays with parchment paper.
Melt the butter and coconut oil (you can melt them together) and allow it to cool as you prep the rest of the ingredients.
In a bowl, add the flour, baking soda, baking powder, cornstarch, cinnamon, and salt. Stir to combine and set aside.
In another bowl, add the melted butter, coconut oil, brown sugar, and white sugar. Whisk to combine and set aside.
Add in egg, yolk, and vanilla. Continue whisking.
Add in the dry ingredients and mix until almost completely combined. Then add in the shredded coconut and chopped pecans. Mix together just until no flour streaks appear.
Scoop 6 cookies at a time, gently press each one down for better spreading. Add extra pecans on top if desired.
Bake for 13-18 minutes. The cookies are ready when the edges are slightly golden brown and the middles are still puffy. They will continue to bake as they cool.
Enjoy! Store them in an airtight container on the counter for 5 days or in the refrigerator for up to 1 week.