Step 1

Preheat oven to 350 degrees F. Coat an 8-inch square baking dish with cooking spray.

Step 2

Sprinkle brown sugar evenly in baking dish and drizzle with butter. Slice 3 bananas in half lengthwise, then cut each of them in half. Layer banana slices cut-side up in baking dish over brown sugar; set aside.

Step 3

In a large bowl, mash remaining 4 bananas. Add eggs, oil, water, vanilla, and sugar; beat with an electric mixer until creamy. Add flour, baking powder, and salt; mix well. Spread batter evenly over bananas.

Step 4

Bake 55 to 60 minutes, or until toothpick inserted in center comes out clean. Let sit 5 minutes, then invert onto platter. Serve warm.