Preheat oven to 350F (175C). Grease and flour a 9x5 inch loaf pan.
In a medium bowl, whisk together flour, baking soda, cinnamon, and salt.
In a separate large bowl, cream together the softened butter and sugar until light and fluffy.
Beat in the eggs one at a time, then stir in the vanilla extract.
In a small bowl, mash bananas.
Add the Greek yogurt to the butter mixture and mix well. Then, add the mashed bananas and combine.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
Fold in the chopped nuts, if using.
Pour batter into the prepared loaf pan and spread evenly.
Bake for 50-60 minutes, or until a wooden skewer inserted into the center comes out clean.
Let the bread cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.
Slice and serve.
Optional Tips:
For a moister bread, add an extra cup of mashed banana.
Substitute applesauce for half the butter to reduce fat content.
Add chocolate chips for a richer flavor.
To prevent the top from browning too quickly, tent the loaf pan with foil during the last 15 minutes of baking.