Ham may be baked in a thousand ways. This particular time we take some cooked diced pork and pair it with cheese and mushrooms.
Preheat your oven to 375°F. Melt the butter in a large nonstick pan over a medium low heat. Saute the onion for 3 minutes, stir occasionally.
Add the mushrooms and continue sauteing for 3 more minutes. Mix in the garlic, pepper and spinach. Cook for 2 minutes, stirring occasionally. All the liquid should almost be evaporated.
Combine the milk, eggs, mustard, ricotta and 1/3 cup Parmesan in a medium sized bowl. Fold in the ham and bread. Then fold in the onion and mushroom mixture.
Place into a lightly grease baking dish, 9"x9"x2". Sprinkle the remaining cheese over the top. Cover with foil. Bake 30 minutes.
Uncover, and place into the broiler, 4 inches from heat. Brown for 1-2 minutes.