For the tomatoes: Preheat the oven to 400˚F. Put the tomatoes on a rimmed baking sheet. Drizzle with the olive oil, salt, and black pepper to taste. Roast for 15 to 20 minutes, until the tomatoes are slightly shriveled. Remove from the oven and let cool. Reduce the oven temperature to 375˚F.
For the mac & cheese: Make sure the oven is still heated to 375˚F. Butter a 9 by 13-inch (3-quart) baking dish or pan (or sixteen 8-ounce ramekins). Set aside.
Fill a 6- to 8-quart pot about three-quarters full with water and add 2 tablespoons of the salt. Bring to a boil and add the pasta. Cook, stirring once or twice, until tender but firm, about 4 minutes, and drain. Reserve the pot.
Place the ciabatta cubes and ¾ cup of the pecorino in a large bowl. Drizzle with ¼ cup of the olive oil and stir to mix. Set aside.
Heat 2 tablespoons of the oil in a large nonstick skillet over medium heat. Add the mushrooms and cook stirring occasionally, until soft, 5 to 7 minutes. Add the oregano and season with salt and black pepper to taste. Set aside.
Using the same pot you used to cook the pasta, heat the remaining ¼ cup oil over medium heat. Slowly whisk in the flour and stir constantly until a paste forms, 30 to 45 seconds. Continue stirring for about 2 minutes more, or until the mixture starts to darken slightly and smell a bit nutty. Slowly whisk in the milk, cream, and the remaining 2 teaspoons salt and cook until the mixture starts to thicken and is just beginning to bubble around the edges, 5 to 7 minutes. It should be thick enough to coat the back of a wooden spoon. Add 6 cups of the mozzarella and the remaining pecorino. Stir until the cheese has melted and the sauce is smooth but not too runny. It should be similar in texture to cake batter. If it’s soupy, continue cooking until it thickens. Add the pasta, mushrooms, pepperoni, tomatoes, olives, and red pepper flakes and stir to combine. Pour into the prepared baking dish. Sprinkle with the remaining mozzarella and top with the ciabatta cubes. Place the dish on a rimmed baking sheet and bake until bubbling and golden brown, about 30 minutes. Let cool for 15 to 20 minutes before serving.
This recipe is excerpted with permission from <a href="http://www.amazon.com/gp/product/1449426468/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=1449426468&linkCode=as2&tag=craftfocom-20">"Mac & Cheese, Please! 50 Super Cheesy Recipes"</a> by Laura Werlin and published by Andrews McMeel Publishing, LLC.