- 1 tablespoon butter (15 g)
- 4 pounds russet potatoes, peeled, cut into 1-inch pieces (450 g)
- 1 cup whole milk (225 g)
- ½ cup 1 stick butter, melted (120 g)
- 1½ cups grated mozzarella (150 g)
- 1 cup freshly grated Parmesan (90 g)
- Salt and freshly ground black pepper
- 2 tablespoons plain dry bread crumbs (30 g)
- Preheat the oven setting it to 400 degrees F; coat a 13x9 2-inch baking dish with 1 tablespoon of butter and set aside for later use.
- Meanwhile, prepare a large deep saucepan and boil the potatoes in salted water until they are absolutely tender, or for about 15 minutes. Drain salted water after potatoes are cooked through. Return the potatoes to the same pot and mash thoroughly.
- Stir in the milk and melted butter after the potatoes are mashed well enough. Add the mozzarella cheese and ¾ cup of Parmesan; sprinkle with salt and pepper for seasoning.
- Transfer the mashed potatoes to the prepared baking dish. In a small bowl, stir in bread crumbs and the remaining ¼ cup Parmesan cheese together and mix thoroughly.
- Sprinkle the bread crumb mixture into the mashed potatoes in the baking dish. Cover and chill; this recipe can be prepared ahead of time for about 6 hours.
- Bake uncovered for 20 minutes, or until topping is golden brown.
- Serve warm and enjoy!