1. Grease a 9×13-inch pan. Cut loaf into cubes and place evenly in the pan.
2. In a bowl, mix eggs, milk, heavy cream, sugar, and vanilla. Pour evenly over bread. Cover pan with plastic wrap and refrigerate overnight.
3. In a medium-sized bowl, mix flour, brown sugar, cinnamon, and salt. Add butter and mix until crumbly. Place in a ziptop bag and refrigerate overnight.