Mississippi Mud Cake

INGREDIENTS

• 1 (1-pound) box confectioners' sugar
• 1 teaspoon vanilla extract
• 2 teaspoons vanilla extract
• 2 cups sugar
• 1/2 teaspoon salt
• 1 stick unsalted butter
• 1/2 cup cocoa
• 3 tablespoons cocoa
• 1/4 cup water
• 1/2 cup vegetable oil
• 6 tablespoons milk
• 2 cups all-purpose flour
• 2 eggs
• 1 cup chopped pecans or walnuts
• 1/2 cup buttermilk
• 1 bag miniature marshmallows
• 1 stick unsalted butter, softened
• 1 teaspoon baking soda