Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
     1/4  cup           butter
   1      cup           brown sugar
   1      cup           sugar
     3/4  cup           sour cream
   1      teaspoon      vanilla
     1/2  cup           chopped walnuts
                        walnut halves
                        melted semisweet chocolate -- (optional)

Preparation:

Melt butter in heavy saucepan. Add brown sugar and heat to boiling. Add sugar and sour cream. Cook over medium heat until dissolves, then on slightly higher heat to 236 degrees on candy thermometer. Without stirring cool to room temperature to lukewarm. Beat until mixture holds its shape and loses its gloss. Quickly stir in vanilla and chopped walnuts. Spreaad immediately in buttered 8 x 8" pan. Cool and cut into squares. Garnish with walnut halves. Drizzle melted chocolate over top.