Grease side and bottom of 2 (10 inch) tube pans.
Prepare Topping; set aside.
In a shallow, medium bowl, dissolve yeast in warm water. Add 1 Tablespoon sugar and half cup flour; stir to combine. Cover; let stand in a warm place 5 to 10 minutes until foamy.
Heat milk and butter or margarine in a small saucepan until melted. Let stand until mixture cools to warm.
In a large bowl, beat eggs, egg yolks and remaining 1 cup sugar until pale and frothy.
Add cooled milk mixture, salt and yeast mixture. Beat unil smooth.
Gradually beat in 4.5 cups flour.
Stir in enough remaining flour to make a soft dough. Turn out dough on a lightly floured surface.
Knead dough into a soft, smooth dough. Divide dough in 0.5. Arrange 1 part dough in each greased pan. Cover with a damp cloth; let rise in a warm place, free from drafts, until doubled in bulk, about 2 hours.
Preheat oven to 180ºC .
Lightly beat 2 egg whites in a small bowl until foamy. Brush beaten egg whites on top of dough.
Evenly sprinkle Topping over dough. Bake 50 to 55 minutes or until a wooden pick inserted in centre comes out clean.
Cool cakes in pans 3 to 4 minutes on racks. Turn out of pans; cool completely on racks.
Frost with Powdered sugar Icing if desired. Makes two (10 inch) cakes.
Topping: In a small bowl, combine sugar, flour, and cinnamon. Using a pastry blender or 2 knives, cut in butter or margarine until mixture resembles coarse crumbs.
Powdered sugar Icing: 2 egg whites 1.5 cups sifted powdered sugar half tsp lemon juice. In a medium bowl, beat egg whites until frothy. Gradually add powdered sugar, beating constantly. Beat 10 minutes or until glossy. Add lemon juice; beat 2 minutes or until icing stands up in soft peaks. Makes about 1.25 cup icing.