COMBINE the condensed milk and chocolate in a small saucepan and gently heat until the chocolate has melted and the mixture is smooth. Transfer mixture to a freezer proof bowl and chill in the freezer for 15 minutes
BEAT the chocolate mixture and PHILLY using an electric mixer, until smooth. Add the cream and beat until soft peaks form. Fold through cherries and then spoon mixture into a freezer proof container. Cover and freeze for 4 hours or overnight
HEAT the extra cream in a saucepan and just bring to a boil, then pour over extra chocolate and butter. Stir until smooth. (Add liqueur if desired)
SCOOP ice cream into sundae glasses and top with chocolate sauce and grated chocolate. Serve immediately