Mac and Cheese

From Epicurious.com

Ingredients

For the topping:

• 2 tablespoons unsalted butter, plus more for baking dish
• 2 tablespoons extra-virgin olive oil
• 2 cups panko (Japanese breadcrumbs)
• 2 large garlic cloves, minced
• 2 ounces finely grated Parmesan (about 1/2 cup)
• 1/2 teaspoon kosher salt

For the macaroni and sauce:

• 1 pound dried elbow macaroni
• 1/2 cup (1 stick) unsalted butter
• 6 tablespoons all-purpose flour
• 4 cups whole milk
• 3/4 cup heavy cream
• 8 ounces coarsely grated Swiss cheese (about 3 cups)
• 8 ounces coarsely grated Gruyere cheese (about 3 cups)
• 2 ounces grated Parmesan (about 1/2 cup)
• 2 teaspoons kosher salt
• 1/2 teaspoon ground white pepper
• 1 1/2 tablespoons mustard powder

Special equipment: 9- by 13-inch baking dish

Preparation

Preheat oven to 400°F with rack in the middle of oven. Butter the baking dish. Set a large, covered pot of salted water over high heat to boil.

Meanwhile, in a large skillet over medium heat, heat butter and oil until butter foam subsides. Add panko and garlic; cook, stirring, until crumbs are golden brown, 4 to 6 minutes. Transfer crumbs to a medium bowl, stir in 1/2 cup Parmesan and salt, and set aside.

Add macaroni to boiling salted water and cook until just al dente (avoid overcooking). Drain macaroni and set aside. In a large wide pot over medium-low heat, melt the butter. Sprinkle flour over butter, whisking to incorporate and make a roux. Cook, stirring constantly with a wooden spoon, until roux is light golden, about 4 minutes. Gradually pour in milk and cream, whisking constantly to incorporate and make a béchamel sauce. Raise heat to medium-high and bring sauce to a low boil, whisking constantly. Reduce to a simmer, whisking occasionally, and cook until béchamel sauce is thick and coats the back of a spoon, about 3 minutes more.

Add the salt, pepper, and mustard powder. Add the cheeses in three batches, whisking until each addition is completely melted before adding more. Remove from heat.

Add the drained macaroni to the pot with the cheese sauce and stir well to coat. Transfer macaroni mixture to the buttered baking dish and place on a rimmed baking sheet. Sprinkle topping evenly over macaroni and bake until golden and bubbling, 18 to 23 minutes. Let cool 15 minutes before serving.