Preheat the oven to 350°F (175°C). Lightly grease a loaf pan or line it with parchment paper so the bread releases easily after baking.

Mash the ripe bananas in a mixing bowl until mostly smooth. A few small lumps are fine, but the texture should be soft and creamy.

Add the rolled oats and ½ cup milk to the bananas and stir well to combine. Mix in a pinch of cinnamon if using. The batter should be thick but easy to scoop—add a tablespoon of milk if it feels too dry.

Pour the mixture into the prepared loaf pan and spread it evenly, smoothing the top so it bakes uniformly.

Bake for 30–35 minutes, until the top is lightly golden and a toothpick inserted in the center comes out clean. If it browns too quickly, loosely cover with foil during the last few minutes.

Let the bread cool in the pan for 10 minutes, then transfer to a rack to cool further before slicing so it holds together nicely.