Preheat the oven to 325 degrees
Grease a 9x5-inch loaf pan with butter
Mix the flour, baking powder, baking soda, and salt in a mixing bowl
Stir bananas, milk, vanilla, and cinnamon in another bowl with a fork
Beat sugar and butter together in a third bowl with an electric mixer for about 1 minute
Mix the eggs into the sugar and butter one at a time until fully mixed
Mix the banana mixture into sugar, egg, and butter mixture
Mix in the flour mixture until just blended
Fold in the chocolate chips and chopped walnuts
Pour the folded batter into the greased loaf pan
Bake in the preheated oven for about 70 minutes. Stick a knife or toothpick in the center; if it comes out clean, it's ready to take out
Cool the banana bread in the pan for at least 30 minutes before serving