FOR THE CARAMEL SAUCE: Combine all of the sauce ingredients in a small saucepan. Stir over low heat until the sugar dissolves. Bring to a boil, reduce heat and simmer, stirring, for 3 minutes.
FOR THE WAFFLES: Combine the melted butter and chocolate and stir vigorously until well combined. Add the sugar and egg yolk and beat well.
Sift together all the dry ingredients and add to the chocolate mixture alternately with the milk. Beat the egg white until stiff. Fold into the chocolate mixture.
Heat a waffle iron and cook the mixture according to the manufacturer's instructions. (It is best to oil the waffle iron for this mixture, as it tends to stick.) Serve immediately with the Caramel Sauce, vanilla ice cream, and shavings of chocolate.