Preheat your oven to 350°F (176°C).
Grease a 9x5 inch loaf pan with nonstick spray.
In a large mixing bowl, mix together the mashed bananas and melted butter. Add the baking soda and salt to the banana mixture and stir to combine. Mix in the sugar, beaten egg, and vanilla extract.
Add the flour and mix until just combined. Be careful not to overmix, as this can make the bread tough. Gently fold in the walnuts. Pour the batter into the prepared loaf pan.
Bake for 50-60 minutes, or until a toothpick inserted into the center of the bread comes out clean. (can check with a toothpick at various times to get an idea of where it is at).
Allow the bread to cool in the pan for 10 minutes.
Brew and prepare the coffee to your liking.
Slice the banana bread then spread it with butter. Serve with coffee.
Wrap the remaining bread tight and freeze or enjoy at your leisure.