In a large bowl, whisk together the egg, brown sugar, coconut oil, granulated sugar, sour cream and vanilla extract. Add flour, baking powder, baking soda, and cinnamon, and fold into mixture.
Add the zucchini, bananas, and blueberries, and fold gently to combine.
Preheat oven to 350F. Grease one 9x5-inch loaf pan ( you an also split the batter into two pans, just be sure to adjust the baking time)
Turn batter out into the prepared pan, smoothing the top lightly with a spatula.
Bake for about 65 -80 minutes or until the top is golden, the center is set, and a toothpick inserted in the center comes out clean. Allow to cool in pan for 15- 20 minutes until transferring to a wire rack.