Classic Baked Macaroni and Cheese Casserole with Cheddar and Gruyère

Ingredients

• Kosher salt
• 1 pound elbow macaroni
• 7 tablespoons unsalted butter, divided
• 2 tablespoons all-purpose flour
• 2 cups milk
• 1 1/2 pounds grated sharp cheddar cheese
• 1 teaspoon hot sauce, such as Frank's RedHot
• 1/2 teaspoon mustard powder
• 1/4 teaspoon garlic powder
• 1/2 pound grated Gruyère cheese
• 1 cup panko bread crumbs

Directions

1. Heat the oven to 400 degrees F (200 degrees C). Bring a medium pot of salted water to a boil, then cook the elbow macaroni until it is just under al dente, about 2 minutes before the package says it will be done. Drain the pasta, move it to a large mixing bowl, and toss it with 2 tablespoons (30g) butter until the butter has melted and the macaroni is coated. Set it aside.
2. In a large saucepan over medium-high heat, melt 2 tablespoons (30g) butter, watching so it does not brown. Add the flour and whisk until it turns into a paste. Cook, stirring, until the flour no longer smells raw, about 1 minute. While whisking the whole time, pour in the milk in a slow, steady stream, making sure to work the whisk into the edges of the pan so the mixture stays smooth. The sauce will get quite thick at first, then loosen once all the milk is in.
3. Cook the sauce, stirring, until it reaches a simmer and starts to thicken a bit. Lower the heat to medium-low, then whisk in the cheddar a little at a time until you have a smooth, cohesive cheese sauce. Once the cheese goes in, do not let the sauce boil. Whisk in the hot sauce, mustard powder, and garlic powder, then taste and add salt if needed.
4. Pour the cheese sauce over the pasta and stir until every piece is coated. Allow it to cool slightly, then stir in the grated Gruyère until evenly distributed. Transfer the pasta mixture to a 9- by 13-inch baking dish and spread the top into an even layer.
5. Put the panko in a small mixing bowl. Melt the remaining 3 tablespoons (45g) butter, pour it over the panko, and stir until the crumbs are evenly coated. Season with salt. Sprinkle the panko evenly over the mac and cheese. Bake on the top rack until the casserole is bubbling and the topping is browned, about 45 minutes, checking often since ovens can vary and the top can darken quickly.
6. Rest the mac and cheese for 15 minutes before serving. Leftovers can be refrigerated for up to 5 days and reheated in the microwave or oven.