This comforting casserole of potato and hard-boiled egg slices jumbled in a creamy sauce is one of the national dishes of Hungary. There it is usually eaten as a meatless main course, often for supper. It also makes a fine brunch or breakfast dish, accompanied by grilled sausages and a green salad.
Cook's Note: Be sure to choose potatoes of similar size so they cook evenly.
1. In a large pot, combine the potatoes with enough cold water to cover by 2 inches and bring to a boil over high heat. Lightly salt the water and cook until the potatoes are barely tender, about 35 minutes. Drain in a colander and rinse under cold running water until cool enough to handle. Peel the potatoes and cut into 1/2-inch-thick rounds.
2. Position a rack in the center of the oven and preheat to 350°F. Generously coat a 13 by 9 by 2-inch glass or ceramic baking dish with the butter.
3. Layer half of the potatoes evenly in the dish with no gaps, cutting the slices as needed to fit. Top with half of the eggs in an even layer. Generously season with salt and pepper. Dollop half of the sour cream on top, then spread it evenly with an offset spatula. Sprinkle with paprika. Repeat the layering with the remaining potatoes and eggs, more salt and pepper, and the remaining sour cream and paprika. Cover the dish with foil.
4. Bake until a knife inserted into the center of the casserole for 5 seconds comes out hot, about 45 minutes. Gently fold everything together to disperse the sauce evenly. Sprinkle with paprika and pepper and serve hot.