Preheat Oven to 350 degrees F.
Grease your loaf pan and line the pan with a parchment loaf liner or cut a strip of parchment paper to fit the bottom. Lightly re-grease the paper liner.
Whisk all your dry ingredients in a small/medium bowl. Flour, Baking Powder, Baking Soda, and Salt. Set aside.
Mash and measure your bananas. Set aside.
In a medium/large bowl, cream softened butter with your mixer (first) then add sugar and blend until light and fluffy.
Add Eggs, Sour cream, Mashed Bananas, and Vanilla. Mix until just combined - do not overmix!
Add your dry ingredients to your wet ingredients. Mix on low until fully combined but again-do not overmix.
Pour Banana Bread batter into your loaf pan. Make sure your top pan edges are wiped clean and flatten batter with a spatula or spoon.
Bake for approx. 1 hr 20-30 minutes depending on your oven. When your bread has no jiggle and looks firm after cook time take out and test with a cake tester or thin skewer. If it comes out clean the bread is done otherwise cook a little longer. Avoid opening the oven door as much as possible until your bread is done.
Allow bread to cool in the pan for approx. 10-15 minutes then edge around the sides with a spatula to loosen the bread from the pan. Tip pan upside-down onto a drying rack, remove parchment paper, then turn the bread right-side-up to cool completely on the rack.
After the bread is completely cooled, seal in cling wrap or an air-tight container. Store at room temperature for a few days or seal in cling wrap then cover with foil to freeze up to 3 months. Enjoy!