Gluten-Free/Casein-Free Banana Nut Bread

Yes, I already posted a recipe for banana bread/muffins, but you know when you have a favorite recipe and you just want 'your' banana bread?  That was me this morning, so I converted my old banana bread recipe so I could have my comfort food back.  It turned out really well, I was quite pleased with them.  I made muffins again, so I could freeze them and just take out a few as we needed them, also instead of nuts I used dairy-free chocolate chips, but my boys love banana chocolate chip muffins (and they don't like nuts).

Banana Nut Bread
1/2 cup sugar
2 tablespoons brown sugar
5 tablespoons dairy-free margarine (I used Nucoa)
1 1/3 cups mashed ripe bananas (2 medium)
1 egg
2 egg whites
1 2/3 cup brown rice flour
1/2 cup potato starch
1/4 cup tapioca starch
1 teaspoon xanthan gum
1 teaspoon baking soda
1/2 teaspoon salt
1/3 cup walnuts, optional
1/2 cup dairy-free chocolate chips, optional (I used Tropical Source)

Directions
1. Preheat oven to 375 F.  Grease a large loaf pan or muffin tins (or line with muffin cups); set aside.
2. Beat sugars and margarine in large bowl until light and fluffy.  Add bananas, egg and egg whites.
3. In separate bowl combine flours, xanthan gum, baking soda and salt; add to banana mixture. Stir in nuts and chocolate chips and pour into prepared pan or muffin cups, smooth out tops with a wet spatula.
4. Bake 1 hour for bread or 20-25 minutes for muffins.  Remove from pan; cool on wire rack.