Preheat oven to 170 degrees C. Grease and flour 2 round 20cm cake tins.
Sift the flour and salt together and set aside. Cream butter and sugar until light and fluffy. Add eggs and mix well. Dissolve bicarb soda in buttermilk. Alternately add flour and buttermilk, beginning and ending with the flour. Divide between the two tins.
Bake for about 30 minutes or until skewer inserted into cake comes out clean. Cool cake completely before icing.
Beat butter and cream cheese together. Gradually beat in icing sugar. Add milk until a icing consistency is formed; add more milk if necessary.