Cooking oil spray
1 box yellow cake mix
3 large eggs
1/4 cup vegetable oil
1/2 cup sour cream
1/2 cup milk
1/2 cup unsalted butter, melted
6 bananas, cut into 1/4-inch-thick rounds
1-1/2 cups unsweetened shredded coconut
3/4 cup (packed) brown sugar
2 tablespoons lemon juice
Preheat the oven to 350 degrees F. Spray a 9-by-13-inch baking pan with cooking spray.
In a large mixing bowl, combine the cake mix, eggs, vegetable oil, sour cream and milk and beat on low speed to combine. Then beat on high for 2 minutes.
Mix the lemon juice with the melted butter, and pour into the prepared cake pan. Sprinkle the brown sugar lemon mix and coconut over it in an even layer.
Arrange the banana slices on top of the sugar and coconut in a single layer.
Spoon the cake batter on top of the topping in the pan, smoothing it into an even layer.
Bake in the preheated oven until a toothpick in the center comes out clean, 35 to 40 minutes.
Remove the cake from the oven and let cool on a rack for 5 minutes before inverting it onto a large serving platter.