The Golden Gratin Mac and Cheese

Preheat the oven to 375 degrees Fahrenheit. Lightly grease a 9x13-inch baking dish with butter and set aside.

Bring a large pot of generously salted water to a rolling boil. Cook the cavatappi for 2 minutes less than the package directions so it remains quite al dente. It will finish cooking in the oven. Drain and set aside.

In the same pot over medium heat, melt the 4 tablespoons of butter. Once it begins to foam, add the flour and whisk continuously for about 2 minutes until the roux turns a light golden color and smells faintly nutty.

Gradually pour in the warm milk in a slow, steady stream while whisking constantly to prevent lumps from forming. Continue whisking until the sauce thickens enough to coat the back of a spoon, about 5 to 6 minutes.

Remove the pot from the heat. Stir in the Dijon mustard, smoked paprika, cayenne pepper, and nutmeg. Add the cubed cream cheese and stir until it melts completely into the sauce.

Add the grated sharp cheddar and gruyere in three additions, stirring after each until fully melted and the sauce is smooth and glossy. Season with the salt and black pepper. Taste and adjust seasoning as needed.

Fold the drained pasta into the cheese sauce until every piece is thoroughly coated. Pour the mixture into the prepared baking dish and spread it into an even layer.

In a small bowl, toss the panko breadcrumbs with the 2 tablespoons of melted butter, the Parmesan cheese, and the fresh thyme leaves until evenly combined. Scatter this mixture over the top of the mac and cheese in an even layer.

Bake uncovered on the center rack for 25 to 30 minutes until the breadcrumb topping is deeply golden brown and the sauce is bubbling vigorously around the edges.

Remove from the oven and let the mac and cheese rest for 8 to 10 minutes before serving. This resting time allows the sauce to thicken slightly and makes for cleaner portions.