In the bowl of a stand mixer fitted with the paddle attachment, mix the flour, baking soda, oats, sugars, salt, milk powder, and cinnamon together, to disperse the soda and break up any lumps of sugar. Add the cold butter and coconut oil, and mix on low speed until the mixture resembles rustic sand, about 4 minutes.
Whisk the egg and vanilla together in a small bowl, and slowly add this to the buttery mixture, on low speed. Once all the egg has been incorporated, add the shredded coconut, and turn the speed to medium to bring the dough together.
Use a spoon to portion the dough into twelve balls, roll them in coconut, and transfer the dough balls to a plate or quarter sheet pan.
Freeze the portioned cookie dough for 30 minutes. While the dough chills, preheat your oven to 375°F (190°C). Line two half sheet pans with parchment.
Place the balls of dough, six to each parchment-lined sheet pan, and bake them both on the center racks of your oven for 10 minutes.
Rotate the sheet pans, and bake for an additional 5 to 6 minutes, until the cookies are risen and browned at the edges, but soft and a bit wet-looking in the center. Remove the cookies from the oven, and rap the pan on the counter to settle them before leaving them to cool for 15 minutes.
They are best eaten warm the same day, but still amazing 2 days later. Cool any uneaten cookies completely, and store them in a sealed container.