all purpose sifted flour
Preheat oven to 350 degrees.
Grease and flour two or three 8 inch layer pans or one 9x12x2 cake pan.
Mix all dry ingredients together.
Blend in mayonnaise, eggs, vanilla and 1/2 of sour cream.
Beat 2 minutes at medium speed with mixer or 300 strokes by hand.
Add remaining sour cream and beat 2 minutes longer.
Bake 25 to 35 minutes until a toothpick inserted in center comes out "clean".
Cool on rack a few minutes before removing from pan.
FROSTING: Cream butter and cream cheese together until fluffy, gradually add dry ingredients one at a time until all are well blended.
Add vanilla and blend well.