Beat butter and cream cheese at medium speed until creamy.
Gradually add sugar, beating until light and fluffy.
Add eggs, one at time, just until blended.
Combine dry ingredients (flour, baking powder, baking soda & salt) in a separate bowl.
Then gradually add to the butter/cream cheese mix at a low speed until just blended.
Mash bananas and stir into mix.
Add pecans (optional) and vanilla.
Spoon batter into 2 greased loaf pans.
Bake for 1 hour at 350.
Watch the bread, if it starts to brown, add tin foil for the last 15 mins to avoid too much browning.
Cool for 10 mins, remove from the pans onto wire racks and cool for 30 mins before slicing.