Preheat the oven to 350°F (175°C), and butter 2 8×4 inch loaf pans.
In a stand mixer bowl, mash the ripe bananas with a paddle attachment until completely smooth. Measure 3 cups of the bananas and put it back in the bowl.
Stir in melted butter.
Mix in the baking soda and salt and stir.
Add in the sugar, beaten egg and vanilla extract and combine.
Add the flour 1 cup at a time and combine until everything is mixed in.
Divide the batter between the 2 loaf pans.
Bake for 50 minutes to 1 hour at 350°F (175°C), or until a tester inserted into the center comes out clean.
Remove from oven and let cool in the pan for 10 minutes. Then remove the banana bread from the pan and let cool completely before serving. Slice with a bread knife and serve.