1 Preheat the oven: to 425ºF. Have readily available a 9- x 13-inch or 2-quart, shallow baking dish.
2 Prepare dinner the potatoes: Wash and minimize the potatoes into 1-inch chunks (peeling non-compulsory). Place them in a big pot. Fill the pot with chilly water till there’s about an inch of water above the potatoes.
Add 2 teaspoons salt and style; the water ought to style as briny as the ocean. If it doesn’t, add just a few extra pinches of salt.
Convey to a boil over excessive warmth. Scale back the warmth to a simmer and prepare dinner the potatoes, uncovered, for 15 to 20 minutes, or till tender when pierced with the tip of a paring knife.
Drain in a colander and return to the potatoes to the pot. Set the pot over low warmth and stir the potato chunks for 1 to 2 minutes to dry them.
three Mash and season the potatoes: Add the butter to the pot of scorching, drained potatoes (nonetheless over low warmth) and mash nicely with a potato masher till the butter melts. There could also be just a few ‘rustic’ lumps. Push the potatoes to at least one facet of the pot to make an area for the milk. Add the milk and warmth it till scorching (this solely takes just a few seconds.)
Use a sturdy whisk to stir within the milk, whisking till the potatoes are fluffy and including extra milk, 1 tablespoon at a time, if the potatoes appear dry. Stir in half cup of the cheese, half teaspoon salt and 1/eight teaspoon pepper. Style, and add extra salt, should you like.
four In the meantime, make the filling: In a big skillet over medium warmth, warmth the oil. Add the onions and garlic and prepare dinner for five minutes, or till softened. If the onions are cooking to quick cut back the warmth to medium-low.
Add the oregano and cumin, and prepare dinner for 30 seconds. Add the beans, corn, rooster, and salsa to the skillet. Stir in half teaspoon salt. Style and add extra salt, should you like.
5 Assemble the casserole: Switch the filling to the baking dish. Unfold the mashed potatoes excessive and sprinkle with the remaining 1 cup cheese.
6 Bake the casserole: Bake for 25 to 30 minutes, or till the filling bubbles and the cheese is golden. Leftovers will hold within the fridge for as much as three days.