Sweet Potato Cake or King's Tart ("Torta do Rei")

Mix the egg yolks and sweet potatoes until you get a light and fluffy cream

Add the sifted flour and cornstarch, and gently fold in the beaten egg whites until stiff peaks form

Melt the butter or margarine (but not too much) and mix with the sweet potato puree

Combine all the ingredients smoothly

Pour the batter into an ungreased and floured cake pan, about 2 inches deep

Bake for about an hour at a moderate temperature

If the cake browns too quickly, cover it with aluminum foil greased with butter or margarine

Remove the cake from the oven while still warm

Dip a wet sponge in milk and spread it evenly over the top of the cake

If desired, sprinkle chopped almonds or candied pecans on top.