Heat convection oven to 375 degrees. Butter 4 8x8 baking dishes, set aside.
Place your chopped crusty bread into a bowl. Over the bread, sprinkle you spices, and toss to coat all the pieces in the spices. Drizzle melted butter over the bread, toss to coat evenly, and set aside.
Fill a large pot with water and, when it comes to a boil, add your pasta and cook per instructions. While you are boiling your pasta, heat another large high-sided saucepan on a separate burner. Melt your butter and, when butter starts to bubble, add in your flour and whisk as you add. Cook for about 1 minute to allow butter and flour to brown.
Slowly pour ½ cup of milk into the pan whisking as you pour – it will thicken almost instantly when it hits the flour/butter mixture. Immediately continue to add milk at about ¼ cup at a time (to temper the mixture as you go), whisking constantly, until all the milk is incorporated. Continue to cook the milk on medium heat until it begins to slightly thicken. Turn off heat. Stir in black pepper, nutmeg, and your cheeses. Give the mixture a stir until cheeses are melted.
Assemble the dish. Distribute your pasta and cheese sauce evenly into each of your 8x8 baking dishes, and stir to evenly coat all the pasta. For your basic Mac, cover the top of the noodles with seasoned bread pieces; set aside. For spicy Mac, stir in the chopped tomatoes and jalapeno pepper. Once incorporated, cover the top of the dish with seasoned bread pieces; set aside. For ham and pea Mac, stir in the peas, prosciutto. Once incorporated, cover the top of the dish with seasoned bread pieces, and sprinkle the dish with the grated parmesan; set aside.
Put Mac and Cheese into oven and bake for approximately 25 minutes, or until bread is browned and cheese is bubbling at the base of the pan.