Bake the potatoes in a preheated 425F. oven for 50 minutes to 1 hour, or until they are soft, halve them lengthwise, and scoop the potato out of the shells with a spoon, reserving the shells for another use. Force the scooped-out potato through a ricer or a food mill fitted with the medium disk into a large bowl. (There should be about 2 cups riced potato.)
In a saucepan combine 1/2 cup water, the butter, the salt, and the nutmeg,
Bring the mixture to a boil, and stir in the flour all at once. Reduce the heat to moderate and beat the mixture vigorously with a wooden spoon for 3 minutes, or until the paste pulls away from the side of the pan and forms a ball. Remove the pan from the heat, add the eggs, 1 at a time, beating after each addition, and beat the mixture until it is smooth and shiny.
Knife, directly into the oil. Fry the croquettes, turning them with a slotted spoon, for 3 minutes, or until they are crisp, golden, and cooked through, transfer them as they are fried to paper towels to drain, and sprinkle them with the salt. Make more croquettes in batches with the remaining potato mixture and transfer the drained croquettes to a rack set
In a jelly-roll pan (to prevent them from becoming soggy). The croquettes
Croquettes in advance, keep them warm in a preheated 300F. oven.