Mix together 15g white rice flour, 12g brown rice, 6g tapioca starch, 6g corn starch, 1g xanthan gum, 1/4c sugar, 1/4t nutmeg, 1/4t pumpkin pie spice in a small bowl.
To dry ingredients add 1T pumpkin puree, 1T canola oil, 1/4t vanilla extract, and 1 egg. Using a fork whisk all ingredients together.
Pour cake mix into mug filling no more then 2/3 full.
Place the cake in a pre-heated oven and bake for 25min.
While the cake cooks in a small mixing bowl add 1/4c powdered sugar, 1t MCT powder (if using), 1/8t Vanilla extract, and 1t of liquid, mixing until combined. You can add up to 1 additional teaspoon of liquid to thin the frosting if you prefer.
Remove the cake from the oven and let cool for 15min before drizzling cake with frosting.
Eat and Enjoy!