Preheat the oven to 325 degrees F. Grease and flour two 9x5-inch loaf pans.
Sift together the flour, baking powder, baking soda, salt and cinnamon.
In a large bowl, use an electric mixer to combine the sugar and butter. Beat eggs slightly, and mix into the creamed mixture with the bananas. Mix in the sifted ingredients until just combined. Stir in the milk and vanilla.
Spread the batter into the prepared loaf pans, and bake for 75 minutes.