Preheat the oven to 350F. In a large bowl, combine the milk, maple syrup, and cinnamon. In another bowl, beat the egg whites until frothy. Add the egg whites to the milk mixture and stir to combine thoroughly. Add the bread and toss well. Set aside to soak for 30 minutes. Fold in the diced apples and raisins and pour into a nonstick or lightly oiled 8x12x2" baking dish. Bake for 45-50 minutes, or until the top is very brown and crisp. A knife inserted into the middle should come out clean at this point. Serve warm or at room temperature.