The offered this today and I was interested as this is a dish I grew up with (see Recipe #451594). This is different from my family's recipe. This one appears creamier as it uses half and half to make a sauce.
COOK MACARONI Adjust oven to middle position and heat oven to 400 degrees. Bring 4 quarts water to boil in large Dutch oven over high heat. Stir in 1 tablespoon salt and macaroni and cook until just al dente, about 6 minutes. Drain pasta and return to pot. Pour diced tomatoes with their juices over pasta and stir to coat. Cook over medium-high heat, stirring occasionally, until most of liquid is absorbed, about 5 minutes. Set aside.
MAKE SAUCE Meanwhile, melt butter in medium saucepan over medium heat until foaming. Stir in flour and cayenne and cook until golden, about 1 minute. Slowly whisk in half-and-half and broth until smooth. Bring to boil, reduce heat to medium, and simmer, stirring occasionally, until mixture is slightly thickened, about 15 minutes. Off heat, whisk in cheeses, 1 teaspoon salt, and 1 teaspoon pepper until cheeses melt. Pour sauce over macaroni and stir to combine.
BAKE MACARONI AND CHEESE Scrape mixture into 13 by 9-inch baking dish set in rimmed baking sheet and bake until top begins to brown, 15 to 20 minutes. Let sit for 10 to 15 minutes before serving.
MAKE AHEAD: Macaroni and cheese can be made in advance through step 2. Scrape mixture into 13 by 9-inch baking dish, cool, lay plastic wrap directly on surface of pasta, and refrigerate for up to 2 days. When ready to bake, remove plastic wrap, cover with foil, and bake for 30 minutes. Uncover and bake until top is golden brown, about 15 minutes. Let sit for 10 to 15 minutes before serving.