Preheat oven to 350F. Combine first 4 ingredients in a bowl. Beat at low speed with an electric mixer until blended; set aside. Bring cola to a boil in a small sauce pan over medium heat. With mixer on low speed, gradually pour hot cola into cake batter. Increase speed to medium, beat 2 minutes. Pour batter into a greased and floured 9 x 13 x 2 inch baking pan. Bake for 30 minutes, or until a wooden pick inserted in center comes out clean. Cool in pan on wire rack 10 minutes. Spread chocolate-cola frosting over top of warm cake, cool cake completely on wire rack.
Combine first 3 ingredients in a large sauce pan; cook over medium heat, stirring constantly until butter melts. (Do not boil). Remove from heat. Add powdered sugar and vanilla, stirring until smooth. Stir in pecans. Spread on warm cake.
Cajun Country -- New Iberia, Louisiana