Preheat the oven to 350°F (175°C).
In a large mixing bowl, combine sliced bananas, sugar, and lemon juice. Stir gently.
In another bowl, whisk together flour, baking powder, and salt.
In a separate bowl, mix melted butter, milk, and vanilla extract until blended.
Gradually add the wet ingredients to the dry ingredients, stirring until just combined.
Pour the banana mixture into a greased baking dish.
Spoon the batter over the banana mixture, distributing it evenly.
Bake in the preheated oven for 35-40 minutes, or until the top is golden brown.
Remove from oven and let it cool slightly before serving.