In a dry cast iron skillet, roast 2 small or 1 medium chile pepper on high heat until skin is blistered and brown. Set aside to cool.
Cook pasta in a large stock pot according to cooking instructions on the package. Make sure the pasta is al dente since it will go in the oven later on. Once pasta reaches al dente, strain and set aside.
Add 1 qt of milk to a saucepan and warm on medium (don't boil).
While the milk is warming, melt 6 tbsp. of butter in a stock pot over medium heat.
Add 1/2 cup flour to the butter and whisk quickly until butter and flour combine. Let the mixture sit on the heat for 2-3 min.
Slowly add the warm milk to the butter and flour mixture, stirring quickly to combine. The mixture should become smooth and thick. If it's runny, turn up the heat on your pot and whisk quickly until it thickens.
Once mixture is thick, take the pot off the heat. Add cheese, nutmeg, smoked paprika, ground mustard seed, salt, pepper, Green Chile Hot Sauce. Stir to incorporate.
Add pasta and roasted chiles. Adjust salt, pepper, and Green Chile Hot Sauce to taste.
Grease shallow sheet pan with sides and add mac and cheese mixture. Set aside.
In a small saucepan, melt remaining 2 tbsp. of butter over medium heat.
Add melted butter to small bowl with salt, pepper, and panko breadcrumbs. Stir to combine.
Top mac and cheese with panko mixture and place in the oven for 30 minutes.