1. Preheat the oven and prepare the pasta

Start by heating the oven to 400 degrees so it is at full temperature by the time the mac and cheese is ready to bake. While the oven preheats, bring a large pot of well salted water to a rolling boil and cook the pasta until just shy of al dente, since it will finish softening in the oven and you want to avoid a mushy texture. Drain the pasta well, then set it aside while you prepare the sauce.

---

2. Crisp the pancetta for savory crunch

Place the diced pancetta in a small skillet with the olive oil over medium high heat, spreading it into an even layer so the pieces brown evenly. Cook, stirring occasionally, until the pancetta is beautifully browned and crispy around the edges, which should take about 3 to 4 minutes. Use a slotted spoon to transfer the pancetta to a small plate lined with paper towel, leaving the rendered fat behind, and set it aside to add later for a salty, savory punch.

---

3. Make a smooth, silky roux

In a large saucepan set over medium heat, melt the butter until it is fully liquefied and just starting to foam but not browned. Sprinkle in the flour and immediately begin stirring, making sure the butter and flour combine into a smooth paste that pulls slightly away from the bottom of the pan. Continue to cook this roux for about 1 minute, stirring constantly, which cooks off the raw flour taste and gives the sauce a more rounded, cooked flavor instead of a pasty one.

---

4. Whisk in the milk and thicken the sauce

With the roux bubbling gently, begin adding the warm whole milk a little at a time, stirring or whisking constantly to avoid lumps and to help the mixture emulsify. Keep adding the milk gradually, making sure each addition is fully incorporated and smooth before pouring in more, until all 2 cups are in the pan and the mixture looks like a thin cream. Continue cooking over medium heat for about 4 to 5 minutes, stirring frequently, until the sauce thickens to a custard like consistency that coats the back of a spoon and leaves a clean line when you run a finger through it. Once thickened, season the sauce with salt and black pepper to taste, remembering that the cheeses and pancetta will add more saltiness later.

---

5. Melt in the trio of cheeses

Remove the thickened white sauce from the heat so the cheese melts gently without breaking or becoming grainy. Add the grated sharp cheddar, grated mozzarella and half of the grated Parmigiano Reggiano directly into the hot sauce, stirring steadily as the cheeses melt into a smooth, glossy, rich cheese sauce. The sharp cheddar brings tangy, pronounced flavor, the mozzarella melts into an oozy, stretchy texture and the Parmigiano adds a nutty, deeply savory note, creating a layered cheese profile that makes the mac and cheese taste more complex. Stir until no shreds of cheese remain visible and the sauce is completely smooth.

---

6. Combine pasta, pancetta and cheese sauce

Add the cooked and drained pasta to the pot of cheese sauce, making sure the pasta is still warm so it absorbs the sauce properly. Tip in the crispy pancetta and gently fold everything together, using a large spoon or spatula to coat each curl of pasta with the creamy cheese sauce while distributing the pancetta evenly throughout the dish. The goal is to have every bite carry a balance of tender pasta, rich sauce and little pops of salty pancetta rather than having all the meat sitting at the bottom of the pan.

---

7. Transfer to a baking dish and top

Spoon the mac and cheese mixture into a casserole dish, scraping the pot to capture every bit of sauce and smoothing the top into an even layer so it bakes uniformly.

Sprinkle the breadcrumbs over the surface, followed by the remaining grated Parmigiano, distributing both as evenly as possible to create a consistent golden crust in every scoop. Finish with a light drizzle of olive oil over the surface, which helps the topping brown more deeply and crisp up in the hot oven.

---

8. Bake until golden and bubbling

Place the casserole dish in the preheated 400 degree oven and bake for about 20 to 25 minutes, or until the top is nicely golden, the edges are bubbling and the breadcrumb and cheese topping has formed a crisp crust. When it comes out of the oven it will smell intensely cheesy and savory, with the top offering a textural contrast to the creamy pasta underneath. Let the mac and cheese sit for about 5 minutes before serving so the sauce can settle slightly, which makes it easier to scoop neat portions without the cheese running excessively.

---

9. Serving and flavor tips

Serve generous scoops of the mac and cheese with a simple green salad on the side to balance the richness and add freshness and crunch to the plate. Because the dish is very rich, it works best as a main course for four rather than a small side, and a crisp salad or some lightly cooked green vegetables keeps the meal from feeling too heavy. This baked version is ideal for entertaining or family dinners because it can be assembled ahead, chilled and baked just before serving, though you may need to add a few extra minutes in the oven if starting from cold.