Preheat oven to 350F and line a large baking sheet with parchment paper.
In a medium-sized bowl, whisk together the almond flour, coconut flour, cornstarch, cinnamon, baking soda and salt.
In a large mixing bowl, use an electric mixer to cream together the butter, brown sugar and granulated sugar until light and fluffy. (This will take about 3-5 minutes).
Add the egg, egg yolk and vanilla and mix again until well combined.
On low speed, mix in the almond flour mixture until just combined.
Add the oats and continue mixing until combined.
Stir in the butterscotch chips (reserving some for the tops of the cookies).
Use a 1.5 tablespoon cookie scoop to portion out the cookie dough and place on the prepared baking sheet about 2 inches apart. (I usually bake 8 per pan).
Use the bottom of a measuring cup or your hand to flatten the cookie dough portions slightly (this will help the cookies spread).
Press some butterscotch chips into the tops.
Bake for 8-10 minutes, or until the cookies start to brown around the edges and still look a little glossy on top. Let cool on the pan for 10 minutes before transferring to a wire rack to cool completely.
Repeat with remaining cookie dough.
Notes
If the cookies spread too much, just use a large round cookie cutter or wide mouth glass to scoot around the cookies to shape them. This works best when the cookies are hot out of the oven.
These cookies will be soft when they come out of the oven but they will firm up as they cool. Let them sit on the pan for 10 minutes before transferring to a wire rack.
I always use light colored pans for cookies because they brown more slowly. If you use a dark sheet pan, just keep an eye on the cookies as they will brown more quickly and could burn on the bottom.
To keep these cookies gluten-free, make sure your oats are certified gluten-free.