Preheat your oven to 350°F (175°C). Grease and flour a standard 9x5 inch loaf pan, or line it with parchment paper for easy removal.

In a large mixing bowl, mash the ripe bananas with a fork until mostly smooth, with a few small lumps remaining. Stir in the melted coconut oil (or butter) and brown sugar until well combined.

Whisk in the egg and vanilla extract until the mixture is smooth and emulsified.

In a separate medium bowl, whisk together the gluten-free flour blend, baking soda, salt, cinnamon, and nutmeg (if using).

Gradually add the dry ingredients to the wet ingredients, mixing gently with a spatula until just combined. Be careful not to overmix, as this can lead to a tough loaf. If using nuts, fold them in now.

Pour the batter into the prepared loaf pan and spread it evenly.

Bake for 50-65 minutes, or until a toothpick inserted into the center comes out clean. The top should be golden brown.

Let the banana bread cool in the pan for about 10-15 minutes before transferring it to a wire rack to cool completely. This step is crucial for preventing it from falling apart.