Serendipity's Frrrozen Hot Chocolate

Why I Love This Recipe
Serendipity's Frrrozen Hot Chocolate has been the signature dessert of Serendipity 3, a restaurant in New York, for over 50 years. Up until a couple of years ago, this recipe was so closely guarded that even Jackie Kennedy was unable to obtain it for a White House dinner.
Ingredients You'll Need
1 1/2 teaspoons Sweetened Van Houton cocoa
1 1/2 teaspoons Droste Cocoa
1 1/2 tablespoons Sugar
1 tablespoon Sweet butter
1/2 cup Milk
3 Godiva flowers, dark and light chocolate; to taste
1/2 ounce Callebaut chocolate
1/2 ounce Valhrona chocolate
1/2 ounce Lindt chocolate
1/2 ounce Cadbury chocolate
1/2 ounce Anton Berg chocolate
1/2 ounce Freia chocolate
1/2 ounce Marabo chocolate
1/2 ounce Girardelli chocolate
1/2 ounce Cocoa Barry (solid) chocolate
Frrrozen Hot Chocolate:
1 Generous ladle of Serendipity's Chocolate Blend
1/2 pint Milk
1/2 quart Crushed ice
Garnish:
1 tablespoon Whipped cream
Chocolate shavings
Directions
In the top of a double boiler over simmering water, melt the first two cocoas with sugar and butter, creaming to a smooth paste.
Add all the remaining chocolates and continue melting, slowly adding the milk in a thin stream to the mixture and stirring constantly until thoroughly blended and smooth as silk.
Cool to room temperature.
In a quart-sized blender, combine Frrrozen Hot Chocolate ingredients. Puree until very thick, pour into a grapefruit bowl, top with whipped cream and sprinkle with grated chocolate.