Preheat oven to 350 degrees
Cream butter and sugar together in a mixer
Blend in eggs, vanilla and sour cream
Mash bananas and mix in with wet ingredients
In a small, separate bowl, sift together flour, baking powder and salt
Slowly add the dry mixture to the wet ingredients until fully combined
Lightly spray a loaf pan and line with parchment, letting the paper fall over the sides
Carefully pour the bread batter into the prepared pan, smoothing out the top
Bake for 60 minutes, until top is golden brown, and a toothpick inserted comes out clean
Serve warm, or allow to cool as you wish