In a bowl of an electric mixer fitted with the paddle attachment, beat the melted ½ cup unsalted butter, 1 cup light brown sugar and ¼ cup granulated sugar for 3 minutes on medium speed until light and fluffy. You can also make these cookies in a large mixing bowl with a whisk, and beat for 5 minutes instead.
Add the 2 large eggs, one at a time, and beat in between each addition just until incorporated. Mix in the 2 teaspoons pure vanilla extract.
In a separate medium bowl, whisk the 2 ½ cups oat flour, 1 tsp baking soda and 1 tsp Kosher salt. Add the dry ingredients to the liquid ingredients and beat on medium-low speed until it begins to incorporate, then increase to medium speed and mix just until a dough forms. If using a regular bowl, switch to a rubber spatula once the cookie dough starts to get thick.
Mix in the 2 cups semi-sweet chocolate chips on medium speed for 10 seconds or fold together with a rubber spatula. Scrape down the sides of the bowl to ensure everything is well incorporated.
Cover the bowl with plastic wrap and chill cookie dough bowl in the fridge for 30 minutes if time allows.
Preheat the oven to 350°F. Line two rimmed cookie sheets with parchment paper.
Scoop 1 ½ tablespoons of cookie dough and place onto the baking sheets at least 2 inches apart. Bake for 10-12 minutes. The cookies will look puffy right after baking and deflate causing beautiful cracks once set.
Let cookies cool on the baking sheet on a wire rack for 10 minutes before carefully transferring them to a wire rack to cool completely.