In a medium bowl, combine the flour, cinnamon, baking powder, baking soda, and salt. Set aside.
In a large bowl, cream together the butter and sugars with an electric mixer until light and fluffy. Beat in the peanut butter and sour cream until smooth and creamy.
Beat in the eggs and vanilla until combined. Mix in the bananas.
Slowly add the dry ingredients to the wet and stir until just combined.
Bake for 1 hour or until a toothpick inserted in the center comes out clean.
Cool in the pan for 10 minutes and then move to a wire rack to finish cooling.
Notes
Bananas should be very ripe for the best banana bread.You can mix in up to a cup of chopped nuts or chocolate chips, if desired.Store banana bread, tightly covered, on the counter for 3-4 days.