Preheat the oven to 350°F. Generously grease a loaf pan or baking dish.
In a small bowl, combine the topping sugar and cinnamon. Sprinkle half of the mixture over the bottom of the prepared pan.
Beat the softened butter and granulated sugar together until well combined.
Add the milk and eggs, mixing well after each addition.
Add the mashed overripe bananas and mix until incorporated.
In a separate bowl, whisk together the flour, baking soda, baking powder, salt, and cinnamon.
Gradually add the dry ingredients to the wet mixture. Mix only until combined.
Pour the batter into the prepared pan and spread it evenly. Sprinkle the remaining cinnamon-sugar mixture over the top.
Place the pan on a foil-lined baking sheet and bake for 60–65 minutes, or until a toothpick inserted into the center comes out clean.
If the top browns too quickly, loosely cover it with foil. Allow the bread to cool slightly before removing and slicing.
