In a medium saucepan, melt butter over low heat. Stir in brown sugar until fully dissolved. Remove from heat, add sliced bananas and toss gently to coat. Pour into a greased cake pan.

In a large mixing bowl, whisk together flour and baking powder. Cream melted butter and sugar until fluffy; add eggs and milk, mixing until combined. Fold in dry ingredients gently.

Pour the batter over the caramelized bananas in the cake pan, spreading it evenly. This will rise and envelop the bananas during baking.

Preheat oven to 350°F (175°C). Bake the cake for 40 minutes or until a toothpick comes out clean. Keep an eye on it as it bakes.

Let the cake cool in the pan for 10 minutes. Run a knife around the edges, then invert onto a serving plate to reveal the caramel topping.