1. Preheat oven to 350°F. Grease or line a cookie sheet with parchment paper. Set aside.

Make the brown butter (I used the technique from The Kitchn)

1. Melt butter over medium heat. Use a pan with a light-colored bottom so you can see the color of the butter change.
2. Swirl the pan while the butter is cooking so it cooks evenly.
3. The butter will begin to foam as it melts and the color will change to a nutty-brown. Once you smell the nutty aroma, take the pan off the heat and pour the browned butter into a glass bowl.

Make the cookie dough

1. In a medium bowl, combine dry ingredients; oat flour, almond flour, 2 teaspoons cinnamon, baking soda, sugar, and salt. Mix to combine and set aside.
2. Combine the wet ingredients (minus the butter): Milk, vinegar, and vanilla extract.
3. Gently pour the wet ingredients into the dry ingredients. Mix to combine. If batter is too dry, add more milk (this depends on the gluten free flour you use).
4. Add 1-2 tablespoons of brown butter to the batter and gently mix again.
5. Place batter in fridge for 30 minutes (or up to 24 hrs.). Alternatively, freeze batter for 15 minutes to chill and thicken. If your batter is thick enough to roll into dough balls, then you will not have to chill long. See notes if the batter is still too soft after chilling.
6. While batter is in fridge, mix 1 teaspoon of cinnamon with a few teaspoons of crystal/fine cane sugar.
7. Remove the batter from fridge. Using a medium size cookie scoop, place batter into your floured hands and roll into a ball. Coat with cinnamon sugar and place on cookie sheet. Repeat until all batter is used up. For flat cookies, use the palm of your hand to flatten the dough.
8. Bake for 12 to 15 minutes. Check at 10 minutes for doneness.
9. Remove cookies from oven and allow them to cool on the pan for 2 minutes before transferring to a wire rack to cool completely.