Preheat oven to 350F. Pour boiling water over chocolate, stirring until melted. Cool. Beat sugar and margarine until fluffy. Beat in egg yolks, one at a time. Add chocolate mixture and vanilla, mix at low speed. Mix in flour, baking soda and salt alternately with buttermilk, beating after each addition until batter is smooth. Beat egg whites until stiff; fold into batter. Pour into prepared pan. Bake about 20 minutes or until toothpick inserted into center comes out clean. Spread caramel topping over hot cake. Sprinkle with chocolate chips and pecans. Bake 20 additional minutes or until chocolate chips melt. Cool before serving.
Cajun Country -- New Iberia, Louisiana