Step 1

In a medium bowl, whisk together the flour, baking soda and salt. Set aside.

Step 2

In a stand mixer fitted with the paddle attachment, beat together the butter, coconut oil, brown sugar and granulated sugar until very light, about 5 minutes. (Make sure you don't see any little pieces of coconut oil. Coconut oil loves to get trapped in the little ridge at the bottom of the mixer bowl. Make sure to scrape it out.) Add the egg and vanilla and beat until well-combined.

Step 3

With the mixer on low, add the dry ingredients and beat just until combined. Add the oats and coconut and mix briefly to combine. Press plastic wrap against the dough and chill it for at least 24 hours and up to 36.

Step 4

Preheat the oven to 375 F. Line a baking sheet with parchment paper.

Step 5

Portion the dough out into 2 to 3 tablespoon scoops and set them on the prepared sheet, about 2 inches apart.

Step 6

Bake the cookies until set and golden brown, about 12 to 14 minutes. Transfer the cookies to a rack to cool. Repeat with the remaining dough.