Stir together flour, baking powder, and 3 tablespoons sugar. Whisk in milk, egg, 1 tablespoon melted butter, and 3/4 cup water until smooth. Cover; let stand 1 hour.
Heat a 12-inch nonstick skillet or a griddle over medium-high heat. Brush with butter. Pour in 1/3 cup batter, swirling to cover bottom. Cook, flipping once, until golden brown, about 2 minutes per side. Repeat with remaining batter.
Melt 3 tablespoons butter in a large skillet over medium-high heat; sprinkle with 3 tablespoons sugar. Arrange half the bananas in a single layer in skillet. Cook, turning once, until golden brown, about 8 minutes. Add a pinch of salt. Repeat with remaining 3 tablespoons each butter and sugar, remaining bananas, and salt.
Place 1 cup banana mixture in center of each pancake. Fold 1 edge over bananas, then the 2 adjacent edges, then remaining edge. Transfer to a plate, seam sides down. Drizzle with condensed milk.