Preheat the oven to 350°F. Spray an 8x5-inch loaf pan with nonstick spray.
In a medium bowl, whisk together the flour, baking soda and salt.
In a separate large bowl, use an electric mixer to combine the sugar and butter at medium speed until well blended (about 1 minute). Add the eggs one at a time, beating well after each addition. Add the banana, yogurt, and vanilla; beat until blended. Stir in the flour mixture- just until incorporated (don't over-mix).
Spoon the batter into the prepared pan. Bake for 50 to 60 minutes or until a wooden pick inserted into the center comes out clean. Cool for 15 minutes in the pan on a wire rack. Remove from the pan and cool completely on wire rack.
Notes
If you come up short on mashed banana, add unsweetened applesauce to make up the difference. It will make your bread nice and moist, and it won't add apple flavor to the bread.