old fashioned brown mountain cake

Ingredients

• 1 cup butter
• 2 cups sugar
• 3 large eggs
• 3 cups sifted flour
• 1 teaspoon baking soda
• 1/2 teaspoon salt
• 3 tablespoons cocoa
• 1 cup buttermilk
• 1 teaspoon vanilla extract
• 1/2 cup warm water
• CARAMEL FROSTING
• 1/2 cup (1 stick) butter
• 2 tablespoons light corn syrup
• 1 cup firmly packed dark brown sugar
• 1/3 cup half and half or evaporated milk (more if necessary)
• 1/2 teaspoon caramel extract
• 1 teaspoon pure vanilla extract
• 1 pound box confectioners sugar
• 2 cups finely chopped black walnuts for garnish (optional)