In a medium sized mixing bowl, whisk together 1 1/2 cups gluten free rolled oats, 1 cup gluten free flour, 1/2 teaspoon baking powder, and 1/4 teaspoon salt.

In another medium sized mixing bowl with an electric mixer or a stand mixer fitted with the paddle attachment, beat 1 stick softened butter with 3/4 cup brown sugar on medium high speed until lighter and fluffier looking (about 30 seconds).

Scrape down the sides of the bowl if needed and on medium high speed, beat in 1 egg until the mixture is smooth, light and fluffy looking once more (30-45 seconds).

To the wet mixture, add the dry mixture half at a time, beating on low at first then mixing on medium speed until completely combined. Stop and scrape the sides of the bowl if necessary.

Mix in 1/2 cup mini chocolate chips and 1/2 cup regular chocolate chips on low speed until completely combined.

Using a large cookie scoop (about 2.5 tablespoons), place heaping scoops of dough onto two baking sheets lined with parchment paper or ideally a silicon baking mat. Use your hands to make the cookie balls taller than they are wide. This will make for nice thick cookies. You should fit about 8-9 cookies on each sheet, evenly spaced. Place the cookie sheets in the freezer for 8 minutes.

After 8 minutes, take the cookie sheets out of the freezer and preheat the oven to 350 degrees. Let the cookies rest on the counter for about 5-6 minutes while the oven preheats. Make sure your oven racks are in the middle most position.

Bake the cookies staggered in the oven (one sheet on bottom left, on on top right) for 6 minutes. Then carefully swap the sheet pans and bake another 5-7 minutes until bottoms are lightly browned. Err on the side of less time or use a thin spatula to check the bottom of one for browning. The cookies will not look quite done in the middle when you take them out. See notes if you would like to bake only one sheet of cookies at a time.

Let the cookies rest and set up for 15 minutes.