Spray and line a 8×11 pan cake pan with parchment paper.
Preheat oven to 350 degrees.
In a large bowl, whisk the sorghum flour, br rice flour, and tapioca starch.
Add cocoa, baking powder and soda.
Whisk again to combine.
In stand mixer, beat butter until creamy.
Add brown plus cane sugar and beat until fluffy.
Add eggs, plus egg yolks one at a time, mixing on low speed.
Add vanilla also.
Once mixed, on slow speed add dry ingredients as well as the buttermilk.
Turn to medium speed and beat for a minute.
Remove bowl from mixer and mix in chocolate chips.
Pour batter into pan and spread evenly.
Bake 30-40 minutes until cake is done.
Enjoy!