Preheat your oven to 350°F (175°C). This ensures that the bread will bake evenly.
Grease your loaf pan with butter or line it with parchment paper for easy removal later.
In a large mixing bowl, whisk together the 6 large eggs, 0.75 cup melted butter, 0.5 cup yogurt, and 0.75 cup mashed bananas until well combined.
In another bowl, mix together 0.33 cup coconut flour, 0.5 cup granulated sweetener, 3 teaspoons cinnamon, and 1.5 teaspoons baking powder. Stir until evenly distributed.
Gradually fold the dry mixture into the wet ingredients using a rubber spatula until just combined. Be careful not to overmix.
If using, fold in the 0.5 cup crushed walnuts and 1 teaspoon vanilla extract at this stage.
Pour the batter into the prepared loaf pan, smoothing the top with your spatula.
Place the loaf pan in the preheated oven and bake for 45-55 minutes, or until a toothpick inserted into the center comes out clean.
Allow the banana bread to cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely. Slice and enjoy!