Delmonico Potatoes

From the landmark New York restaurant Delmonicos is one of their signature dishes.

2¼ lbs all-purpose potatoes
2 tbsps minced onion
5 tbsps unsalted butter
3 tbsps flour
1½ cups milk
½ cup heavy cream
⅓ cup freshly grated Romano
⅓ cup freshly grated Parmesan
3 hard-boiled large eggs, chopped coarse
1½ cups fresh bread crumbs

1. In a kettle, cover the potatoes with cold water, bring the water to a boil, and simmer the potatoes for 30 minutes, or until they are tender. Drain the potatoes, let them cool until they can be handled, and peel them. Cut the potatoes into ½-inch dice and in a bowl, chill them, covered.
2. In a saucepan cook the onion in 3 tbsps of the butter over moderate heat for 2 minutes, or until it is softened. Stir in the flour and cook the roux over moderately low heat, stirring, for 3 minutes. Remove the pan from the heat, add the milk, scalded, in a stream, stirring, and cook the sauce, stirring, for 2 minutes. Stir in the cream and salt and pepper to taste.
3. In a bowl combine the potatoes, the Romano, the Parmesan, the eggs, and salt and pepper to taste. Spread ¼ cup of the sauce in a buttered 10-inch round oven-proof serving dish, spread half the potato mixture over the sauce in the dish, and top the mixture with half the remaining sauce. Spread the remaining potato mixture in the dish and spoon the remaining sauce over it.
4. In a small bowl combine the bread crumbs and the remaining 2 tbsps butter, melted, sprinkle the crumbs over the sauce, and bake the potatoes in a preheated 350°F oven for 45 minutes, or until the top is golden.

Serves 6.