Preheat your oven to 350°F (175°C). Grease or line a loaf pan with parchment paper. In a medium bowl, whisk together flour, baking soda, salt, and cinnamon (if using). Set aside. In a large bowl, combine mashed mango, sugar, oil, eggs, and vanilla extract. Mix until smooth.

Gradually add the dry ingredients to the wet mixture. Stir until just combined — do not overmix. Gently fold in chopped nuts if using. Pour the batter into the prepared loaf pan. Bake for 50–60 minutes or until a toothpick inserted into the center comes out clean. Let the bread cool in the pan for about 10 minutes, then transfer to a wire rack to cool completely.