In a medium bowl, stir together the flour, sugar, cocoa, baking soda, baking powder, salt and cinnamon. Add the eggs and oil, mix well. Fold in the last three ingredients until they are evenly distributed.
Pour into a greased and floured 9x13 baking pan, and bake at 350°F for 50 to 60 minutes. Cool completely before frosting.
For Frosting: combine all ingredients and beat well until smooth.
Notes
Flour Blend Used: 2 cups sorghum 2 cups potato starch 1/2 cup coconut flour 1/2 cup brown rice flour