Grease several baking sheets; line with parchment or waxed paper. Preheat oven to 275 F (135 C). In a very clean grease-free bowl, beat egg whites until very stiff, but not dry. Add 1/2 tablespoon of the 1/2 cup sugar; beat until sugar is incorporated and meringue is stiff and shiny. Add remaining sugar, a little at a time, beating well after each addition. Beat in vanilla. Carefully fold in chopped marrons glaces. Using two small teaspoons, spoon small oval shapes of mixture onto prepared baking sheets. Lightly sprinkle remaining 2 teaspoons sugar over meringues. Bake meringues 1-1/4 hours or until crisp and dry on outside, but soft in the center; cool. Sift hot chocolate mix lightly over each meringue. Remove meringues from paper.