In a medium bowl, whisk together the gluten-free flour, almond flour, baking soda and salt. Set aside.

Melt the butter in a medium skillet over medium-low heat, stirring occasionally.

Once the butter is melted and begins to foam, stir continuously to prevent the milk solids from sticking to the skillet. The butter will change from yellow to golden brown quickly and will have a nutty aroma. Remove from the heat and immediately pour into a medium bowl.

Add the milk, brown sugar and granulated sugar to the brown butter. Whisk to combine.

Whisk in the egg and vanilla until smooth and creamy.

Using a rubber spatula, mix in the dry ingredients until well-combined. Stir in the chocolate chips.

Cover the bowl and let the dough sit at room temperature for 30 minutes, or refrigerate for up to 5 days.

Preheat the oven to 350°F. Line large baking sheets with parchment paper or silicone baking mats.

Scoop the cookie dough into round balls, about 2 tablespoons per ball. Place on the prepared baking sheet, about 2 inches apart.

Bake for 10-12 minutes or until the edges are golden brown and the center is set.

Remove from the oven and cool on the baking sheet for 5 minutes. Sprinkle with flaky salt, if desired. Transfer to a wire rack to cool completely.