Preheat your oven to 325°F and grease a 3-quart (9x13") baking dish. Because nobody likes scrubbing off baked-on cheese later.
Pasta Time
Bring a large pot of salted water to a boil. Toss in the shells and cook it exactly one minute less than the package says for al dente. Trust me, it’s going to keep cooking in the oven. Drain and set aside.
Cheese Strategy
Shred all that glorious cheese and mix it together. Divide it into three piles:
1.5 Lbs for the sauce
.75 lbs for the middle layer
.75 lbs for the topping
Yes, this is a three-layer cheese situation. You're welcome.
Making the Cheese Sauce (aka Liquid Gold)
Melt the butter in a large saucepan over medium heat. Whisk in the flour and stir until it looks like wet sand. Let it cook for a minute (we're getting rid of that raw flour taste).
Now, pour in about 2 cups of half and half while whisking like you mean it. Once smooth, add the rest of the half and half and whole milk. Keep whisking until it thickens to a condensed soup-like consistency – thick but still pourable.
Cheese Meltdown
Remove the sauce from heat and stir in your spices (salt, pepper, smoked paprika). Then, gradually add 1 ½ cups of shredded cheese, stirring until melted. Repeat with another 1 ½ cups of cheese. Smooth, cheesy perfection achieved.
The Big Mix
In a large bowl, combine the drained pasta with your cheese sauce and all that glorious green chile. Stir like your life depends on it.
Layer It Up
Pour half of the mac and cheese into your prepared baking dish.
Sprinkle it with 1 ½ cups of shredded cheese.
Top with the rest of the mac and cheese.
Because if we’re doing this, we’re doing it right.
Crunchy Topping
Mix the melted butter with the panko breadcrumbs. Stir in the final 1 ½ cups of cheese and sprinkle this over the top.
Bake & Broil
Pop that masterpiece into the oven and bake for 15 minutes until it's bubbling and slightly golden. If you want that perfect crispy top (you do), switch the oven to broil for a minute or two until you reach your desired level of crunch.
Devour
Let it sit for 5-10 minutes before digging in (yes, patience is hard, but worth it). Then, grab a fork and prepare to be obsessed.