In bowl for an electric mixer beat butter and sugar together until light and fluffy, about 2 minutes.
1/2 cup butter, 1 cup granulated sugar
Add eggs, milk and vanilla. Mix until well combined. Beat in bananas. With the mixer at low speed, gradually add in the flour mixture until just combined.
Pour batter into the loaf plan. Bake for 55-60 minutes, until a tester comes out clean. If it is getting too brown on top and not cooked, place foil over the top and continue cooking.
Remove from the oven, and let cool 15 minutes before removing from the pan.