Butter both sides of the 16 slices of bread. Place 8 slices in a 8x10 pan which is 2 inch deep. Cover the bread with the sharp cheese and ham slices. Top this with the remaining 8 slices of bread. Mix the eggs, milk, mustard and salt together. Pour over the casserole and refrigerate overnight. The next morning, combine ½ cup butter and the cornflakes and put on top of the casserole. Bake for 1 hour at 350F.
