Preheat oven to 350º. Grease 2 loaf pans.
Combine milk, vinegar, and baking soda in small bowl and set aside.
Cream butter & sugar; add eggs & beat well.
Add milk mixture, bananas, vanilla, and mix until blended.
Add flour and cinnamon (and nuts, if you choose) and mix well.
Divide batter between 2 loaf pans. Sprinkle tops with cinnamon sugar.
Bake 45 mins - 1 hour until a toothpick inserted into the center comes out clean. (Loaves will come out dark)
[Note: for muffins bake about 12 - 15 minutes, or until baked thru. Makes about 30 muffins]
Let rest in pan 5 minutes, then turn out onto a cooling rack and allow to cool completely before slicing.
Once the bread has cooled completely (if you can wait that long) slice, and enjoy!