Step 1Place the gelatin, sugar and salt in a large bowl. Add the boiling water and stir until completely dissolved, at least 3 minutes. Stir in the cold water. Refrigerate until slightly thickened, about 10 minutes.
Step 2Beat the whipping cream and peppermint extract with an electric mixer on medium speed until soft peaks form, 2 to 3 minutes. Gently stir the cream mixture into the chilled gelatin until well blended.
Step 3Pour into molds, dessert glasses or a large glass dessert bowl. Refrigerate until set, 3 hours. Garnish with chocolate shavings, if desired.