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

Stir buttermilk pancake mix and water together in a bowl. Let batter stand, 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 from oven.

Set oven rack about 6 inches from the heat source and preheat the oven's broiler.

Broil pancake until browned, 1 to 2 minutes. Cool for 2 minutes. Slice with a pizza cutter or cookie cutters.