2poundsRusset potatoes, peeled and cut into small dice
Turn on the broiler and place a rack 5 inches away from heating element. Line a cast-iron skillet or baking sheet with foil and place the Hatch chiles on the skillet. Cook under the broiler for 7 minutes, and then remove the skillet from the oven. Turn over the Hatch chiles and continue to broil the chiles for 7 to 8 more minutes or until nicely charred. After this time, remove the skillet from the oven. Place the chiles in a paper sack or plastic food-storage bag, close it tight and let the chiles steam for 20 minutes. After the chiles have steamed, remove from the bag and rub off the skin. Remove the stems and seeds from the chiles then dice.
Preheat oven to 350° F.
In a large cast-iron skillet set on medium-low heat, melt 2 tablespoons of the butter and then cook the onion until it starts to brown a bit, about 7 minutes. Add the garlic and cook for 30 more seconds. Turn off the heat.
Add the diced potatoes, chiles, garlic, cumin, salt, black pepper, and cayenne pepper to the skillet and mix well with the onions and garlic.
Pour the cream over the potatoes and cover the skillet with foil. Bake for 1 hour.
After an hour, remove the potatoes from the oven, and turn on the broiler. Cut the remaining 2 tablespoons of butter into small pieces, and dot on top of the cooked potatoes. Place the skillet under the broiler for 2 minutes or until the butter has melted and potatoes are starting to brown on top.
Let the casserole cool for 10 minutes, then serve.