Contest-Winning Chocolate Potato Cake- 1 cup butter, softened 2 cups sug…

Contest-Winning Chocolate Potato Cake- 1 cup butter, softened 2 cups sugar 2 large eggs, room temperature 1 cup cold mashed potatoes (without added milk and butter) 1 teaspoon vanilla extract 2 cups all-purpose flour 1/2 cup baking cocoa 1 teaspoon baking soda 1 cup whole milk 1 cup chopped walnuts or pecans CARAMEL ICING: 1/2 cup butter, cubed 1 cup packed brown sugar 1/4 cup evaporated milk 2 cups confectioners' sugar 1/2 teaspoon