Preheat oven to 350° FGrease 8 1/2 x 4 1/2 loaf pan or line with parchment paper. Place the 4 dates in a cup of hot water to soften about 5 min.
Place the sugar in a small bowl and zest the orange into it. Rub the orange zest into the sugar with your fingers.
In a large bowl, combine the flour (plus xanthan gum if needed), baking powder and salt. Add in the sugar with the orange zest and mix well.
Drain and chop the dates into small pieces then add to the flour mixture stirring to ensure they are coated in the flour.
In a separate bowl combine egg, mashed banana, vanilla, milk, oil, and orange juice. Mix well.
Add the wet ingredients to the dry ingredients, stirring until moistened.
Add batter to the greased or lined loaf pan.
Cut a whole banana in half lengthwise and place the cut side facing up onto the batter.
Sprinkle the top of the batter with raw or turbinado sugar. (Optional)
Bake at 350°F for approx 1 hour or until tester comes out clean.
Cool in pan 10 min, then remove to cooling rack to finish cooling.
Cool completely before cutting into it.