Scald the milk and set aside to cool.
Cream the sugar, butter and egg yolk.
Add to this the lukewarm milk, alternately with the flour and the dissolved yeast cake.
Beat lightly and add the stiffly beaten egg white.
Allow this mixture to rise over night.
Flour a bake-board and take out large spoonfuls of the dough to which just enough flour has been added to permit it to be rolled into flat cakes.
Spread on well-greased pie tins and when light (about 1-1/2 hours) brush melted butter over the top and strew thickly with brown sugar.
If preferred, spread "rivels" on top by combining 1/2 cup sugar, 1/2 cup flour, and 2 Tbsp butter.
Crumble together and sprinkle on top of cakes.
Bake at 400-F about 20 minutes.