New England Hot Chocolate

1/4 cup granulated sugar
1 tablespoon baking cocoa
1/8 teaspoon salt
1/4 cup hot water
1 tablespoon butter or margarine
4 cups milk
1 teaspoon maple flavoring
1 teaspoon vanilla extract
12 large marshmallows, divided

In a large saucepan, combine sugar, cocoa, and salt. Stir in hot water and butter; bring to a boil. Add the milk, maple flavoring, vanilla extract and 8 marshmallows. Heat through, stirring occasionally, until marshmallows melt. Pour into four mugs and top each with a marshmallow.