Potato Cake (Pinza di Patate)

8 large Idaho potatoes 3 T. olive oil
3 eggs 1/2 c. freshly grated Parmesan cheese
Salt to taste 2 T. all-purpose flour
3 T. butter, melted 1 egg yolk, lightly beaten
Butter 8-inch cake pan with removable bottom. Fill large saucepan
two-thirds full with water, add potatoes, bring to a boil. Boil gently
until potatoes are tender. Preheat oven to 350 degrees F.(175C).
Peel and mash potatoes while hot. Beat 3 eggs with salt in large
bowl. Beat in melted butter and oil. Add mashed potatoes, Parmesan
cheese and flour; mix well. Put potato mixture into buttered pan and
smooth top with spatula. Brush top with beaten egg yolk. Bake 20 to
25 min. or until top is golden. Unmold potato cake and place on a
warm platter. Serve immediately. Makes 6 to 8 servings.