Mix the sorghum flour, buckwheat flour, potato starch, quinoa flour, xanthum gum, baking powder, baking soda, chocolate chips and salt very well and keep aside.
PREHEAT OVEN TO 350 degree F. Butter the bundt pan very very well and coat it lightly with a dusting of potato starch.
With a beater, whip the butter till it's fluffy. Add the sugar and brown sugar and beat. Add in the eggs one at a time and beat well. Add the vanilla extract and mix in.
Mix in the mashed bananas and apple sauce. Fold the dry ingredients with the butter mixture with a plastic spatula well.
Pour in the bundt pan (ONLY fill 3/4 of the pan ) and lightly tap the pan on a toweled surface 3 times. Bake at 350 degrees F for 55- 65 minutes depending on the oven.
If you see the top browning too fast, reduce the temperature of the oven to 325 degrees F. Remove from oven and let it cool for 15 minutes EXACTLY before un-molding. Enjoy!
Note: It is a dense cake and a slow bake. Leave it on a cooling rack for 15 minutes EXACTLY (not more or less) and then invert it onto a platter. ONLY fill 3/4 of the pan. Butter the bundt pan very very well.