HEAT ½ cup sweetened condensed milk and water in small saucepan over medium heat, stirring occasionally, until mixture comes to a gentle boil. Remove from heat; add rum and coffee granules, stirring vigorously until coffee is dissolved. Set aside.

MIX cream cheese, remaining 1/2 cup sweetened condensed milk and vanilla extract in small mixer bowl until smooth.

WHIP cream and sugar in small mixer bowl until stiff peaks form. Stir one-fourth of whipped cream gently into cream cheese mixture. Fold remaining whipped cream into cream cheese mixture.

LINE bottom of 8-inch-square baking dish with half of sponge cake slices; drizzle with half of coffee mixture. Spoon half of cream cheese mixture over sponge cake slices; top with remaining sponge cake slices. Drizzle with remaining coffee mixture. Spoon remaining cream cheese mixture over sponge cake slices. Refrigerate for 2 hours before serving. Sprinkle with chocolate; serve immediately.