• Preheat the oven to 500°F. If you're using a baking stone/steel, place the stone/steel in the bottom third of the oven before you start preheating. Let the oven preheat for at least 30 minutes.

To make the mac and cheese

• Bring a pot of salted water to a boil and cook the pasta to al dente, according to the package directions. Drain the pasta, return it to the pot, and toss with the truffle oil.
• Pour the milk into a small saucepan and warm it over medium-low heat just until it gets hot and steamy, being careful not to let it boil.
• In a separate, heavy-bottomed saucepan, melt the butter over medium-high heat. Whisk in the flour and cook for 1 to 2 minutes, whisking constantly, until it forms a smooth, bubbly paste. (Be careful not to let it brown.) Pour in the hot milk and whisk for 3 to 5 minutes or until the sauce thickens. Season to taste with salt and pepper, then bring the sauce to a boil, reduce the heat to low, and cook for 2 more minutes. Stir in the paprika, mustard, ¾ cup of the Cheddar, and ¾ cup of the fontina. Stir until the cheeses are completely melted, then add the chives, heavy cream, and pasta, scraping any extra oil from the bottom of the pot. Mix gently until well combined, then taste and season with additional salt, pepper, and truffle oil as desired.

To make the pizza

• Stretch or roll out your dough to a 12- to 14-inch circle, then transfer it to an oiled or parchment-lined baking sheet or a lightly floured pizza peel (if using a baking stone/steel).
• Brush the dough lightly with olive oil and parbake it for 3 to 5 minutes or just until the edges of the crust begin to brown. Remove the crust from the oven.
• Spoon the mac and cheese onto the par-baked crust and spread it out, leaving a ½-inch border of dough all around. To avoid overloading the crust, use just enough mac and cheese to make a ¼- to ½-inch-thick later. (Store the leftovers in an airtight container in the refrigerator for up to 1 week.) Sprinkle the remaining ¼ cup of Cheddar and ¼ cup of fontina over top.
• Return the pizza to the oven and bake for 8 to 12 minutes, until the crust is blistered and the cheese begins to brown in spots. Transfer the cooked pizza to a cutting board.
• Let the pizza rest for 5 minutes, then slice and serve.