Preheat oven to 350°F. In large bowl, cream butter and sugar with electric mixer until light and fluffy. Add eggs, one at a time, and vanilla; beat thoroughly. Combine flour with salt. Combine sour cream with baking soda. Add flour mixture alternately with sour cream mixture; beat well. Pour into prepared pan. Bake 20-25 minutes or until toothpick inserted comes out clean. Cool 10 minutes in pan on rack; remove and cool completely before decorating.