Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking dish with butter or cooking spray.

In a large mixing bowl, mash the ripe bananas until smooth. Add melted butter, sugar, eggs, milk, and vanilla extract; mix until smooth.

In a separate bowl, whisk together flour, baking powder, and cinnamon. Slowly incorporate this dry mixture into the banana mixture.

On a lightly floured surface, roll the dough out into a rectangle about 1/4-inch thick.

Spread softened butter over the rolled-out dough and sprinkle the cinnamon-sugar mixture.

Carefully roll the dough tightly to create a log and slice into 1 to 1.5 inches thick portions.

Place the rolls in the greased baking dish and bake for 25–30 minutes, until golden brown.

Remove from oven and cool for about 10 minutes before serving.