Mississippi Mud Cake IV

INGREDIENTS

• 1 cup butter or margarine, softened
• 2 cups white sugar
• 4 eggs
• 2 teaspoons vanilla extract
• 1 1/2 cups all-purpose flour
• 1/3 cup unsweetened cocoa powder
• 2 teaspoons baking powder
• 1/4 teaspoon salt
• 1 cup chopped walnuts
• 6 cups miniature marshmallows
• 1/2 cup butter or margarine, softened
• 3 1/2 cups confectioners' sugar
• 1/2 cup evaporated milk
• 1/8 teaspoon salt
• 1 teaspoon vanilla extract