Preheat oven to 325 degrees.
Cream butter and sugar.
Add eggs and soured milk. Mix.
Add dry ingredients and mashed bananas.
Pour into 2 greased loaf pans or 1 Bundt pan.
Bake until golden (approximately 1 hour for loaf pans, 1 hour, 30 min. for Bundt pan) and toothpick inserted comes out clean.
Transfer to rack and cool 10 minutes.
Remove from pans and continue to cool.