1. Prepare Your Baking Dish: First, preheat your oven to 375°F (190°C) if baking immediately. Then, thoroughly grease a 9×13 inch baking dish with butter. This prevents sticking and ensures easy serving.

2. Layer the Bread: Next, arrange the torn or cubed bread evenly over the bottom of the prepared baking dish. This forms the base and soaks up all the eggy goodness.

3. Add Ham and Cheese: Now, sprinkle the diced cooked ham over the bread layer. Follow this by distributing both shredded cheddar and Monterey Jack cheeses evenly over the ham. You want cheesy goodness in every bite!

4. Whisk the Egg Mixture: In a large bowl, crack the 8 large eggs. Pour in the 2 cups of milk. Add the Dijon mustard, onion powder, garlic powder, salt, and black pepper. Whisk everything together thoroughly until the mixture is well combined and slightly frothy. This ensures even flavor distribution.

5. Pour Over Layers: Carefully pour the egg mixture evenly over the bread, ham, and cheese in the baking dish. Make sure all the bread pieces get a good soaking. Gently press down any floating bread with a spatula to ensure it absorbs the liquid.

6. Chill (Optional for Make-Ahead): If you are making this ahead, cover the baking dish tightly with plastic wrap or aluminum foil. Refrigerate it for at least 2 hours, or preferably overnight, allowing the flavors to meld and the bread to fully absorb the egg mixture. If baking immediately, proceed to the next step.

7. Bake the Casserole: Uncover the casserole if it was chilled. Place the baking dish in your preheated oven. Bake for 45-55 minutes, or until the casserole is puffed, golden brown, and set in the center. A knife inserted into the center should come out clean.

8. Rest and Serve: Once baked, remove the casserole from the oven. Let it rest for 5-10 minutes before slicing and serving. This resting time helps it set further and makes for cleaner cuts. Garnish with fresh chopped parsley if desired. Enjoy your simple, nourishing breakfast!