Spread the softened butter across the bottom and sides of a 9x13 casserole dish.
Cube your bread (about 1-1.5 inches). Place the bread in the prepared 9x13 dish.**If your bread has a thick or tough crust remove that and discard, only using the inside, soft parts of the bread.
Add your cubed ham on top of the bread cubes, then sprinkle on the cheese.
In a bowl whisk together eggs, milk, mustard, and seasonings.
Pour the egg mixture evenly over top of the bread/ham/cheese. Cover and refrigerate over night (12-24 hours). Can be made 2 days in advance.
Baking
Preheat the oven to 375°. Meanwhile, uncover the casserole and set on the counter.
Once the oven is fully heated, bake uncovered for 45 minutes.
Let the casserole rest for about 10-15 minutes before slicing.
Bread - this recipe is a great way to use up day old bread. I call for "French bread" however you can use what you have. If you have sourdough, use it. If you have leftover rolls, use them. I have made this with leftover slider buns, and it worked great! Ham - if using leftover ham you will need about 2 ½-3 cups. If you are purchasing a ham steak grab one that is about 1- 1.25 lbs. That gives you enough meat after you have trimmed the bone and the fat.