• Preheat the oven to 350°F (175°C). Lightly grease a 9x5-inch loaf pan or line with parchment paper for easier removal.
• In a large bowl, whisk together the flour, baking soda, baking powder, salt, and sugar.
• In a blender, combine the peeled bananas, chia seeds, soy milk, vegetable oil, spinach, and vanilla (if using). Blend until smooth and creamy.
• Pour the blended wet ingredients into the dry ingredients. Stir gently with a spatula or wooden spoon until just combined—do not overmix.
• Pour the batter into the prepared pan and smooth the top. Bake for 50 minutes, or until a toothpick inserted in the center comes out clean.
• Cool the loaf in the pan for 10 minutes, then carefully transfer to a wire rack to cool completely before slicing.

Storage

• Store in an airtight container at room temperature for up to 3 days or refrigerate for up to 1 week. Bread may dry out faster if refrigerated. To freeze, wrap tightly and store for up to 2 months. Reheat slices in the toaster or microwave before serving.