• Chop the semi sweet chocolate and place in a heat proof bowl.
• Heat up the ¾ cup heavy cream in the microwave or in a small sauce pan on the stove until steaming. Then pour over the chopped chocolate. Let it sit for 5 minutes.
• Mix the vanilla extract and instant coffee together to dissolve.
• Whisk the cream and chocolate mixture until melted then add in the powdered sugar, vanilla instant coffee mixture, and mix until fully combined. Let the ganache cool down completely.
• When the ganache is cooled down (about 10-15 minutes), star whipping the 1 cup of heavy cream until stiff peaks form. Don't overwhip the cream or it will turn into butter.
• Take half the amount of whipped cream and gently fold it into the chocolate ganache mixture. Add in the rest of the whipped cream and fold again. Don't overmix the chocolate pie filling, stop when you don't see any more white streaks of whipped cream.
• Pour the chocolate mousse mixture into the Oreo pie crust, loosely cover with plastic wrap, and chill for 5 hours or overnight.

Make the whipped cream topping and assemble

• Once you're ready to serve your pie, whip the one 1 cup of heavy whipping cream with the sugar, and vanilla extract together until stiff peaks form. Top the chocolate pie with the whipped cream and dust with cocoa powder.