In a large bowl, using an electric mixer, cream the butter and sugars until light and fluffy, about 2 minutes. Add egg and mix thoroughly.
In a medium bowl, whisk together the oat flour, baking powder, baking soda, and salt, then mix it into the butter mixture until well combined. Add the oats and chocolate chips on low speed and mix until well blended.
Place the dough in the fridge to chill for 1 hour or up to 3 days.
When ready to bake the cookies, heat the oven to 350°F and line two baking sheets with parchment paper.
Scoop out tablespoons of batter, roll them into balls, and place them on the prepared sheets about 1 inch apart. Place in the oven and bake for 15-20 minutes until lightly browned. Remove cookies from oven, cool on pan for 5 minutes, then place cookies on a wire rack to cool completely.
Cookies may be stored in an airtight container at room temperature for 5 days.