1 1/2 c. butter, softened
3 c. sugar
1 1/2 tsp. baking soda
1 1/2 c. buttermilk
1 tsp. vanilla

Cream butter, gradually add sugar, beating well with electric mixer. Dissolve soda in buttermilk. Add to creamed mixture beating well. Cook in large heavy pan. Stir constantly until 234 degrees on candy thermometer or soft ball stage. Remove from heat and add vanilla. Do not stir. Cool about 10 minutes.

Beat on medium speed of electric mixer until thick enough to spread. Spread immediately on cooled cake. Enough for 3 layer cake.