Instructions

Spray a 13X9-inch baking dish with cooking spray and add the bread cubes.
In a mixing bowl, whisk together the egg whites, eggs, milk, sugar, cinnamon, vanilla and salt. Pour over the bread, cover, and refrigerate at least 8 hours or overnight.
Thirty minutes before baking, preheat oven to 350°F. Take the baking dish out of the refrigerator, and remove the berries from the freezer if using frozen. If using fresh, slice strawberries (if using) and toss all berries with 1 Tbsp. of sugar in a bowl. Set aside.
Place covered baking dish in the oven, and bake for 30 minutes.
In a small bowl, cut the butter into the brown sugar until crumbly. Sprinkle that, and the berries over the French toast, and bake uncovered for another 15-20 minutes, or until a knife inserted in the center comes out clean.