Preheat the oven to 350° F. Grease a 9x5 inch bread pan.In a bowl, stir together the mashed bananas, coconut oil, maple syrup, eggs, and vanilla until combined. Add the flour, baking soda, cinnamon, and salt, mix until just combined. Fold in the walnuts, if using. Pour the batter into the prepared pan. Bake for 50-60 minutes, or until the center is just set. Remove and let cool for 30 minutes before cutting...or just eat it warm with a smear of cinnamon butter. Enjoy!To make the cinnamon butter, In a bowl, beat the butter, maple syrup, cinnamon, nutmeg, allspice, ginger, cloves, and a pinch of salt. Serve with the warm bread.