Sift flour, baking powder, sugar and salt into bowl. Add buttermilk, egg, and butter. Beat to smooth batter. Mash 2 bananas and mix thoroughly into batter with orange zest. Let stand 5 minutes.
lightly grease a griddle pan or skillet and heat over medium heat. Spoon 1/4 cup of batter into pan and cook til bubbles appear on the surface. Turn over with spatula and cook other side til golden brown. Repeat this process using the remaining batter, while keeping the cooked pancakes warm.
For maple butter, beat together butter and maple syrup. Beat til light and fluffy. slice remaining banana and serve with pancakes, with the maple butter spooned over the pancakes. For a subtly different finish, replace the maple syrup int he butter with an equal quantity of a delicately flavored clear honey, such as orange blossom