• Preheat your oven to 350°F. Grease and line a standard 9 x 5 inch loaf pan, and set it aside.

Make the batter.

• In a large bowl, place the flour, xanthan gum, baking soda, baking powder, salt and sugar, and whisk to combine well.
• Add the coconut oil, eggs, vanilla, then the yogurt, mixing until just combined after each addition.
• Add the mashed bananas and mix them carefully into the batter, taking care not to further mash the bananas.
• Transfer half of the banana batter to the prepared loaf pan and spread it into an even layer with a wet spatula. Set both aside briefly.

Make and add the swirl.

• In a small bowl, place all the swirl ingredients and mix to combine well. It will be a thick mixture.
• Place about one half of the swirl mixture on top of the batter already in the loaf pan and spread it gently into an even layer.
• Top with the remaining banana batter and spread that with a wet spatula into an even layer. Finish with the remaining swirl batter and spread again gently into an even layer.
• With a butter knife held perpendicular to the bottom of the loaf pan, swirl the batter from one short side to the other of the pan, back and forth in a looping pattern.
• Smooth the top of the swirled batter into an even layer once more.

Bake the banana bread.

• Place the pan in the center of the preheated oven and bake for 45 minutes. The loaf should be until golden brown on top, and mostly firm toward the center.
• Lower the oven temperature to 325°F and continue to bake until completely firm when pressed lightly in the center, another 10 to 15 minutes.
• Allow the bread to cool in the pan for 10 minutes before transferring to a wire rack to cool completely before slicing and serving.
• Leftovers can be wrapped very tightly and stored at room temperature for up to 3 days, and frozen for longer storage.