Preheat your oven to 350 degrees. Grease a 9x13 baking pan with butter or coconut oil. Set aside.

In a large mixing bowl whisk together gluten free flour, baking powder, baking soda and salt. Set aside.

In the bowl of your stand mixer add the granulated sugar, brown sugar and butter. Blend until they are creamed together. Add the eggs, sour cream, vanilla and milk. Blend just until combined.

Add the dry ingredients to the wet and blend just until combined.

Remove the bowl from your mixer and using a spatula mix the mini chocolate chips into the cake batter.

Pour the batter evenly into your greased 9x13 baking pan. Sprinkle 2 tablespoons of granulated sugar and 1/4 cup of mini chocolate chips evenly over the top.

Bake at 350 degrees for 30-35 minutes or until the top is lightly browned and a toothpick comes out clean.

Let the cake cool completely before slicing and serving.

Store the leftover cake in an air tight container. I love this 9x13 pan with a lid for making and storing cakes.