Combine half the cherries and the sugar in a small saucepan and cook until the cherries are softened. Mix in the remaining cherries, remove from the heat and allow to cool completely.
Whip the cream, sour cream and vanilla to stiff peaks, then fold in the sweetened condensed milk and cherry sauce. Spoon one third into a loaf pan then top with half the chocolate sauce, chopped chocolate and salt flakes. Add another layer of cherry mixture, then more chocolate and salt, before finishing with the remaining cherry mixture. Freeze for 4 hours, until firm.