Step 1

Preheat oven to 350°F and line a large baking sheet with parchment paper.

Step 2

In a medium mixing bowl, sift together the oat flour, tapioca flour, sweet rice flour, cocoa powder, baking soda, and salt. Set aside.

Step 3

In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugars together starting on low speed and increasing to medium high speed, until light and fluffy, 3-5 minutes. Scrape down the sides and add the egg and vanilla and chocolate extracts and beat until just combined.

Step 4

With the mixer on low speed, slowly add the dry ingredients until just combined. Add about 2/3 of the chopped chocolate or chocolate chips and beat for a few seconds until evenly distributed.

Step 5

Scoop 1½ tablespoon-sized balls and place them 2½ inches apart on the parchment-lined baking sheet (I use the OXO medium cookie scoop and it makes exactly 19 cookies). Press 1-2 chocolate chunks onto the top of each cookie dough ball.

Step 6

Bake in batches, if needed, for 10 minutes. Let cool for two minutes on the baking sheet before transferring to a cooling rack with a thin metal spatula to cool completely. Sprinkle with flaky salt, if desired.