01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together oats, gluten-free flour, baking soda, baking powder, salt, and cinnamon.
03 - In a large bowl, beat softened butter, brown sugar, and granulated sugar until light and creamy.
04 - Add egg and vanilla extract to the butter mixture; mix until combined.
05 - Add the dry ingredients to the wet ingredients; stir until just combined.
06 - Gently fold in raisins and walnuts if using.
07 - In a small bowl, mix melted butter, brown sugar, and cinnamon to make the cinnamon swirl.
08 - Scoop dough (about 2 tbsp per cookie) onto prepared baking sheets, leaving 2 inches apart.
09 - Use your thumb or the back of a spoon to make a shallow indent in each dough mound. Fill each indent with about 1/2 tsp of cinnamon swirl mixture.
10 - Use a toothpick to gently swirl the cinnamon mixture into the top of each cookie.
11 - Bake for 12-14 minutes or until edges are golden and centers are set.
12 - Cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.