Instructions
Preheat and prep
1
Heat the oven to 375°F / 190°C and butter a 9×13-inch baking dish.
2
Grate all the cheese before you start the sauce.
Boil the pasta short
3
Salt a big pot of water heavily, add the elbows, and cook two minutes less than the box says.
Build the roux
5
Melt 4 tbsp butter in a large heavy pot over medium heat.
6
Whisk in the flour and cook 90 seconds, until it smells like popcorn and turns pale gold.
Add the dairy
7
Slowly pour in the warm milk and cream while whisking constantly.
8
Simmer 4 to 5 minutes until it thickly coats the back of a spoon.
Season, then melt in cheese
9
Off the heat, whisk in the Dijon, smoked paprika, nutmeg, and salt.
10
Add cheddar and Gruyère by the handful, stirring until each addition disappears before adding the next.
Combine and top
11
Fold in the drained pasta.
12
Tip everything into the buttered dish.
13
Toss the panko with 2 tbsp melted butter and half the Parmesan, then scatter it evenly across the top with the remaining Parmesan.
Bake, then broil
14
Bake 25 minutes until bubbling at the edges.
15
Move the rack to the top third, flip the broiler to high, and broil 90 seconds to 2 minutes until the crust turns copper.
Rest before serving
16
Let the dish sit 10 minutes on the counter.
