Combine cocoa, sugar and pinch of salt in a heavy saucepan. Add the boiling water, and stir over medium heat until the sugar melts and you achieve a thick liquid. Stir in milk and heat until very hot, but not boiling. Stir in vanilla, peppermint extract and half-and-half, and remove from heat. Divide the hot chocolate between 4 mugs. Top each serving with whipped cream and a sprinkling of crushed peppermint candy. Enjoy!