Preheat oven to 350 degrees.
Gather the ingredients.
Line 1-2 cookie sheets with Parchment Paper or a baking pad. Set aside.
Using a stand mixer, with the paddle attachment, combine the Brown Sugar and Softened Butter until light and fluffy.
Next, add the Vanilla and the Eggs, one at a time, scraping down the sides of the bowl after adding each Egg.
In a separate bowl, combine the GF Flour, Salt and Baking Soda until well-blended.
Slowly add the Flour mixture to the Butter mixture, one cup at a time, mixing until just combined after each addition.
Next, add the Oats (and Chopped Nuts, if using), one cup at a time, scraping the sides of the bowl after each addition. Mix until all Oats are blended (be sure to check the very bottom of the bowl for any dry oats).
Using a cookie scoop or spoon of your desired size (I used a 2" cookie scoop), drop cookie dough balls onto prepared cookie sheets several inches apart (they spread!)
Bake for 12-14 minutes (longer if you want crispy cookies).
Cool on the cookie sheets for about 2 minutes before transferring them to a wire cooling rack.
Enjoy with a cold glass of milk or a bowl of Vanilla Ice Cream :)