1. In a deep bowl, combine the yams, butter, onion, parsley, salt and a liberal grinding of pepper, and mix well.
2. Drop in the egg yolks and beat vigorously with a large spoon until the mixture is fairly smooth and thick enough to come away from the sides of the bowl in an almost solid mass.
3. Line a large shallow baking dish with paper towels and place it in the oven. Preheat the oven to the lowest setting. In a heavy 10- to 12-inch skillet, heat the oil over moderate heat until a light haze forms above it.
4. For each cake, drop about a tablespoon of yam mixture into the hot oil. Cook 4 or 5 at a time, leaving space between them so that they can spread into 2- to 2½-inch rounds.
5. Fry the cakes for about 4 minutes on each side, or until golden and crisp around the edges. As they brown, transfer the "Frituras de Name" to the lined dish to drain and keep warm. Serve at once.
