Melt 1 tablespoon butter in large saucepan over medium heat. Add oats and toast, stirring constantly, until fragrant and golden, about 2 minutes.
Add water and bring to boil over high heat. Reduce heat to medium-low and simmer gently, stirring occasionally to avoid scorching, until mixture is creamy and oats are tender but chewy, about 20 minutes.
Off heat, stir in ¼ teaspoon salt, cover, and let stand for 5 minutes. Stir in bananas, sugar, and remaining 1 tablespoon butter. Season with salt to taste. Serve immediately.
