Step 1

Sift together flour, baking powder, baking soda and salt. Set aside.

Step 2

Cream butter until smooth and fluffy, about 3 minutes. Add sugar gradually, usually in 3 parts, until creamy and fluffy,

Step 3

Add eggs to the butter mixture one at a time and then the 2 egg yolks until well mixed. Next, add the vanilla and blend well.

Step 4

In a separate bowl, add the 2 egg whites and cream of tartar and whip to near to stiff peak phase. Set aside.

Step 5

Alternate adding flour and buttermilk to the butter mixture until blended.

Step 6

Fold into the batter mixture the egg whites with cream of tartar.

Step 7

In two 9-inch cake pans, spray with oil having placed two 9-inch rounds of parchment or waxed paper on the bottom of pans. Add 1 Tablespoon flour to each pan; and shake to dust interior sides and bottom.

Step 8

Divide the cake batter evenly into the cake pans. Level the batter in the pans. Place in a 350 degree Fahrenheit oven and bake for 35 minutes or until cake tester comes out clean. Remove from oven and completely cool in pans before removal to spread with frosting.