Put the potatoes in a large pan, cover with water. Add a pinch of salt and bring to a boil. Simmer until tender, about 20 minutes. Drain and return to the saucepan. Cook for 1 minute over high heat, shaking the pan frequently to dry out. Put the potatoes thru a ricer into a large bowl. Stir in the egg, butter, dry milk, cheese, flour, and nutmeg: season with salt. Using floured hands, roll the potato mixture into 1" balls; it makes about 60. Preheat the oven to 350 degrees. In a large nostick skillet, heat 1/2" oil until shimmering. Working in taches of 12, fry the potato balls until browned on 3 sides, 2 to 3 minutes per side. Drain on paper towels, season and transfer to a large, rimmed baking sheet. Reheat in the oven for about 10 minutes. Serve.
These are really versatile - I have made them with onion added etc. You can use your ingenuity. I usually add a little garlic powder and/or seasoning salt.