Make Crust: In a food processor, pulse Oreos into coarse crumbs. Add butter and blend until completely combined.
Press crumb mixtures onto bottom and evenly up sides of a 9" pie dish. (Try to make crust about ⅛"-thick evenly all around.) Refrigerate at least 1 hour before adding filling.
Make Filling: Add chocolate chips and ¾ cup cream to a microwave-safe bowl. Microwave on high for 1 to 2 minutes, stirring every 30 seconds, until smooth. Cool to room temperature, then stir in sugar and vanilla and set aside.
In the bowl of a stand mixer, beat remaining ¾ cup cream until soft peaks form. Beat in chocolate mixture ⅓ at a time until well mixed. Spoon filling into chilled pie crust and smooth top. Refrigerate until firm, about 6 hours.
Make Ganache: Just before serving, add chocolate chips and cream to a microwave-safe bowl and cook on high for 1 to 2 minutes, stirring every 30 seconds, until smooth. Spread over top of pie and let cool. Sprinkle with flaky sea salt.
