Preheat oven to 375 degrees F. Line two baking sheets with parchment paper or silicone baking mats.
Combine the butter, brown sugar, and granulated sugar in the bowl of a stand mixer fitted with the paddle attachment.
Mix on high until light and fluffy, about 3 minutes.
Add the eggs and vanilla and mix until fully incorporated, about 1 minute.
Add the flour, oats, cinnamon, salt, baking soda, and coconut, if using, and mix until just combined, about 30 seconds.
Put the powdered sugar in a small bowl.
Scoop and roll the dough between your palms into golf-ball-sized balls.
Toss in the bowl of powdered sugar until completely covered and arrange the cookies 2 to 3 inches apart on the lined baking sheet.
Bake the cookies for 9 to 10 minutes until golden brown and crackled.
Let cool completely on pans.