Preheat oven to 425°F (220°C). Cover an 11x17-inch baking pan with aluminum foil and grease with cooking spray.

Stir buttermilk pancake mix and water together in a bowl. Let batter stand for about 10 minutes.

Pour batter into the prepared pan, spreading to the corners. Scatter chocolate chips, bananas, strawberries, and blueberries on top.

Bake in the preheated oven until pale and set, about 12 minutes. Remove pan from oven.

Set oven rack about 6 inches from the heat source and preheat the broiler. Broil pancake until browned, 1-2 minutes.