Carefully melt 3/4 bag of chocolate chips in microwave or a double broiler. Until smooth and melted. (takes about 1-2 minutes in microwave, so set for one, stir, and continue, 20 seconds at a time, stirring each time, until melted. Set aside
In mixing bowl, combine cream cheese, butter, sugar and vanilla and beat until smooth.
Add melted chocolate and continue to mix until well combined.
Carefully fold in whipped cream until all incorporated and combined.
Spoon into crust and top with remaining chocolate chips.