Grease and flour an angel food cake pan.
Preheat oven to 300 degrees.
Cream sugar and butter. Add eggs, one at a time, beating after each addition. Sift flour and soda together. Beat in flour and sour cream alternately, beginning and ending with flour. Add vanilla and beat well.
Pour batter into prepared pan. Bake at 300 degrees for 1 hour and 30-40 minutes. Cool in pan on rack until easy to handle. Remove from pan and continue to cool completely.
Though an 8 ounce carton of sour cream is less than a cup, it works fine.
This recipe is too much for my 10 cup Bundt pan. It retains its height and lightness best if baked in a deep rather than a wide tube pan.
Bring butter to near room temperature, but do not warm
in microwave to melt.