Preheat the oven to 375°F (190°C). Line 3 baking sheets with parchment paper.
In a large bowl, stir together the oat flour, all-purpose flour, baking powder, baking soda, and salt.
In the bowl of a stand mixer fitted with the paddle attachment on medium-low or with a handheld mixer on medium-high, beat the butter and both sugars until fluffy, 3 to 5 minutes.
Add the eggs, 1 at a time, pausing after each addition to scrape the sides of the bowl with a spatula. Stir in the vanilla.
Add the flour mixture gradually, in 2 to 3 additions, scraping the sides of the bowl after each addition. Stop using the mixer and gently stir in the chocolate chips, grated chocolate, and nuts. Drop 1-inch balls or blobs of the chocolate chip cookie dough 2 inches apart on the prepared baking sheets.
Bake the cookies for 8 to 10 minutes, or until lightly browned. Let cool for a couple of minutes before carefully transferring the cookies to a wire rack to cool completely. The cookies will be rather tender and delicate, so treat them accordingly. (You can store the cookies in an airtight container at room temperature for up to 7 days or in the freezer for up to 1 month.)