Mix together 4 cups flour, 1 teaspoon salt and 1/4 cup sugar. Cut in two sticks margarine.
Dissolve yeast in 1/4 cup warm water, then add three beaten egg yolks to yeast mixture. Add 1 cup scalded and cooled milk. Mix well. Split dough into two equal halves. Refrigerate overnight wrapped in plastic wrap.
Pre-heat the oven to 375°F.
Roll out dough halves and brush with melted butter. Sprinkle with 1/2 cup sugar and 1 1/2 teaspoons cinnamon. Roll up. Cut. Place rolls in greased dish. Cover with kitchen towel and let rise for 1 hour. Bake in the oven for 20-25 minutes.
While the rolls are baking, make the icing: blend 1 1/2 cups powdered sugar, 1 1/2 teaspoons vanilla extract, 2 tablespoons margarine and 1-3 tablespoons hot water, as needed. Remove rolls from oven and spread icing over the rolls. Serves 6