Melt the butter in a pan or microwave per the instructions above.
Make the crêpe batter: In a large mixing bowl, whisk together the flour and the egg. Gradually add in the milk and water, stirring to combine. Add the salt and butter; beat until smooth.
Heat a griddle or frying pan over medium-high heat. While the pan is heating, prep the fruit.
Prepare the banana and strawberries per the instructions above.
Cook the crêpes: Lightly grease the griddle or frying pan with nonstick spray. Pour or scoop the batter onto the pan, using approximately 1/4 cup for each crêpe. Tilt the pan with a circular motion so that the batter coats the surface evenly. Cook the crêpe for about 2 minutes, until the bottom is light brown. Loosen with a spatula, turn, and cook the other side. Repeat for remaining crêpes.
To finish the crêpes: Place the banana and strawberries inside the crêpe shell (save some for topping), drizzle with maple syrup and fold or roll up.
To serve: Serve crêpes dusted with powdered sugar, and serve with milk.