To make the streusel - Stir together brown sugar, flour, and butter until crumbly, using a fork. Stir in oats and pecans. Set aside.
To make bread pudding - Preheat oven to 375°. Whisk together flour and next 2 ingredients just until blended; whisk in melted butter. Pour batter into a lightly greased 11- x 7-inch baking dish. Top with banana slices, and sprinkle with Streusel Topping.
Bake at 375° for 40 to 45 minutes or until golden brown and bubbly. Serve with ice cream.