Banana Oat Snack Cake

Name: Banana-Oat Snack Cake
Ingredients: 6 tablespoons unsalted butter, cut into ½” pieces, melted, plus more for baking dish; 1½ cups old-fashioned oats; 1 cup all-purpose flour; 2 teaspoons baking powder; 1 teaspoon ground cinnamon; 1 teaspoon kosher salt; 1¼ cups (packed) light brown sugar; 2 large eggs; 1 teaspoon vanilla extract; 3 bananas, chopped