Heat milk to boiling in the top of double boiler and let it cool until lukewarm.
Cream together the butter, sugar, salt, and egg yolk. Add milk and flour, alternately, to the above mixture.
Place yeast in the warm water, stir to dissolve and then add to the mixture. A Beat egg white until stiff and add to batter. Allow to rise in covers bowl overnight or until light.
Divide into 4 parts and pat each into a greased pie pan. Let rise 1 1/2 hours.
Combine the coffee cake streusel topping ingredients in a separate bowl and use a fork to make a crumb mixture. Evenly sprinkle the crumbs over each coffee cake. Bake for 20 minutes at 425° F.