Preheat oven to 350°F.
Arrange bread cubes in a single layer on a large baking sheet. Bake at 350° for 10 minutes or until toasted, stirring once.
In a large bowl, whisk together milk, sour cream, and eggs until smooth. Stir in tomatoes and garlic. Add bread; stir gently to combine. Let stand 5 minutes.
Pour half of bread mixture into a 13 x 9 inch baking dish coated with cooking spray. Arrange prosciutto and BelGioioso Fresh Mozzarella evenly over bread mixture. Top with remaining bread mixture.
Bake for 20 minutes. Sprinkle evenly with BelGioioso Parmesan and bake an additional 20 minutes. Remove from oven and let stand 5 minutes. Serve warm.
May be chilled up to 8 hours or overnight and then baked.