Preheat oven to 400 degrees.

In a large bowl, combine white rice flour, starch, xanthan gum, and granulated sugar.

In a medium-sized saucepan, place 1 c. butter, water and ¼ c. cocoa powder and heat to a boil. Stir constantly for 1 minute and then pour mixture over flour ingredients in the bowl.

Using a handheld mixer or whisk, stir in ½ c. milk. Once batter has reached room temperature or cooler, add eggs, baking soda and vanilla. Mix until combined. Batter will be slightly lumpy.

Spray a 10 x 15 inch sheet cake pan with non-stick cooking spray and pour in batter. Bake for 18-22 minutes.

During the last 10 minutes of baking, bring ½ c. butter, 3 T. cocoa powder and ¼ c. milk to a boil in the saucepan, stirring constantly.

Once a boil is reached, turn off heat and add powdered sugar 1 c. at a time, whisking well after each addition. When all sugar has been added, stir in vanilla. Lastly, mix in pecans.

Pour frosting over cake as soon as it comes out of the oven. Let cake cool completely before serving. Enjoy!