Spray a 9x13-inch baking dish with nonstick cooking spray.
In a saucepan over medium heat, melt butter and whisk in brown sugar, maple syrup and salt until smooth; remove from heat and set aside.
Spread half the bread in the bottom of the prepared pan.
Top with half the sauce mixture and one can drained peaches. Repeat layers.
In a mixing bowl, whisk together egg whites, milk, maple syrup, protein powder and vanilla extract.
Pour egg mixture evenly over bread, cover and place in the refrigerator for at least 4 hours, but preferably overnight.
Preheat oven to 350 degrees F.
Uncover and bake for 1 hour, or until golden brown on top and set in the center.