In a large bowl, use an electric mixer to combine the softened butter, brown sugar, vanilla, cinnamon, nutmeg, baking soda, baking powder, and salt. Beat until smooth.
Add the mashed bananas, honey, eggs, and sourdough discard. Beat until smooth.
Mix in the all-purpose flour and nuts, if desired, until the batter is moistened. Pour the batter into a 9x5 loaf pan that has been sprayed with nonstick spray or lined with parchment paper and allow to rest for 10 minutes.
Bake the banana bread at 325 degrees for 45 minutes then place a loose piece of foil over the pan. Continue to bake for an additional 25 minutes. Insert a toothpick into the center of the loaf. If the toothpick comes out crumb-free, remove from the oven. If not, bake in 5-minute increments until the bread is done.
Remove from the oven and allow the bread to cool for 10 minutes before transferring to a cooling rack to cool completely.