Step 1

For the casserole: Preheat the oven to 375°F. Generously butter a 13-by-9-inch baking dish.

Step 2

In a small bowl, stir together the sour cream and onion soup mix. Refrigerate while you prepare the potatoes so the flavors have time to meld.

Step 3

Place the potatoes into a large pot and cover them with cold water by 1 inch. Bring the water to a boil over high heat and cook until the potatoes are fork tender, 20 to 25 minutes.

Step 4

Drain the potatoes well and return them to the same pot. Place the pot back on the same burner (heat turned off) and mash until there are no visible lumps.

Step 5

Add the prepared onion dip, melted butter, heavy cream, bacon, monterey jack cheese, fried onions, and salt, and stir to combine. Season to taste with pepper. Transfer the mashed potatoes to the prepared baking dish, spreading them evenly.

Step 6

For the topping: In a small bowl, stir together the fried onions, potato chips, and parmesan. Sprinkle the mixture evenly over the top of the mashed potatoes. Bake until bubbling and browned on top, 15 to 20 minutes. Sprinkle with chives just before serving.