Preheat the oven to 375°. In a deep, 2-quart baking or soufflé dish, melt the butter in the microwave. Whisk in the superfine sugar and banana, mashing until thoroughly combined. Whisk in the egg and milk.

In a bowl, whisk the flour, baking powder and salt; whisk into the baking dish until combined (the batter will be pretty loose).

In a microwave-safe cup, heat the maple syrup, light brown sugar and 1/2 cup of hot water at high power until hot, 1 minute. Add the bourbon. Drizzle the syrup mixture over the batter; it will seep to the bottom. Do not stir. Scatter the pecans on top.

Set the dish on a rimmed baking sheet and bake for 40 minutes, until the cake is golden. Let cool for 5 minutes, then scoop into bowls and serve with ice cream. Drizzle some of the syrup in the bottom over the cake.