Place the chopped Dairy Milk bars in a large glass bowl. Place the bowl over a pot of simmering water. Stir continuously until chocolate is semi-melted.
Over medium heat, in a pot gently stir 1 cup of heavy cream for 2 minutes. Gently add the semi-melted chocolate and mix until completely melted. Mix salt.
Remove from the heat, cover and place in the refrigerator for 25 minutes.
Using an electric mixer, mix the remaining 1 cup of heavy cream until it stands in peaks. Gently fold in the caster sugar.
Fold in the chocolate mixture into the whipped cream until well combined.
Fill the serving bowls halfway with mousse, add a generous layer of the Crackle shavings, and fill with the remaining pudding.
Garnish with the remaining Crackle.
Refrigerate for 3 hours until it is ready to be served.