Pueblo Green Chile Mac & Cheese

Method

1. Heat the oven to 375°F and butter a 9x13-inch baking dish with the 1 tsp butter. Boil the macaroni in 4 quarts of water with ¼ cup Diamond Crystal kosher salt for 3 minutes less than the package says, then drain.
2. Melt 4 tbsp butter in a 5-quart pot over medium heat. Cook the onion 4 minutes until soft, add the garlic for 30 seconds, then whisk in the flour and cook 1 minute, until it smells like cooked dough.
3. Whisk in the warm milk in three additions, smoothing each before the next. Simmer 5 to 6 minutes, whisking, until the sauce coats a spoon and holds a finger-drawn line.
4. Take the pot off the heat. Stir in the mustard, cumin and salt, then the cheeses in handfuls, letting each melt before the next. Taste and add salt if needed, then fold in the chiles and pasta.
5. Scrape into the baking dish and set it on a rimmed baking sheet. Toss the panko with the remaining 1 tbsp melted butter and a pinch of salt, scatter it over the top, and bake 20 to 25 minutes, until bubbling at the edges and golden, then rest 10 minutes.