Preheat oven to 350º. Spray a 9x5-inch loaf pan with baking spray with flour. (I used four mini pans - 5 ¾ x 3 ¼ x 2 ¼. Don’t fill more than ⅔ full.)

In a small bowl, whisk together flour, baking powder, baking soda and salt; set aside.

Combine sugar, melted coconut oil, sour cream, eggs and vanilla in a large mixing bowl; beat until well blended. Stir in bananas. Add flour mixture to banana mixture, stirring just until moistened.

In a medium microwave safe bowl, melt chocolate chips in microwave on 50% power, stirring often. Cool slightly. Stir in 1 ½ cups batter until blended.

Using a scoop, put scoops of the chocolate and vanilla batters in the prepared pan(s). Spread the batters so they touch each other and the sides of the pan. Make a second layer of batter, placing scoops of vanilla batter on top of the chocolate, and the chocolate batter on top of the vanilla. Firmly tap the pan two or three times on the counter to level the batter. Using a butter knife, zigzag the knife through the batter to swirl the batters, do a figure 8 through the pan twice. Don’t over mix the batters; you want to create a marbled look, not stir the batters together.

If using, sprinkle turbinado sugar on top of the batter right before baking.

Bake for 1 hour and 5 minutes or until a wooden pick inserted in the center comes out clean. (Bake mini loaves for 30 minutes.)

Cool 10 minutes in pan on a wire rack; remove from pan, and cool completely on a wire rack before cutting.