Preheat oven to 475°F.

Prepare 12 muffin cups (each ½-cup capacity) by spraying each muffin cup with cooking spray or greasing individually.

Combine flours, zanthan gum, baking powder, soda, salt, ground flax seeds, and rolled oats together in a large bowl. Whisk ingredients well to combine. Make a well in the center of the dry ingredients. Set aside.

In separate medium-sized bowl or large measuring cup, whisk together the brown sugar, eggs, coconut oil, maple syrup, and vanilla. Stir in the mashed banana, yogurt, and milk.

Pour wet ingredients into well in dry ingredients. With large spoon, mix ingredients together just until dry ingredients are fully incorporated. Do not overmix. Fold in chopped dates.

Spoon batter into prepared muffin cups, filling almost to the rim of each cup. Transfer to pre-heated oven and immediately reduce oven temperature to 400°F. Bake for 16-18 minutes, or until muffins are just firm to the touch and a cake tester inserted into center of a muffin comes out clean. Do not overbake or muffins will be dry. Remove from oven and let muffins rest in pans for 5-7 minutes then gently remove from pan and transfer to wire rack to cool completely.