• Preheat your oven to 350°F (175°C).
• In a food processor, pulse the Oreo cookies (with the cream filling) until they turn into fine crumbs.
• In a mixing bowl, combine the Oreo crumbs with the melted butter. Stir until the crumbs are evenly coated.
• Press the mixture into the bottom and up the sides of a 9-inch (23 cm) pie dish.
• Bake the crust in the preheated oven for about 8-10 minutes. Remove from the oven and allow it to cool completely.

For the Chocolate Mousse Filling:

• In a microwave-safe bowl, combine the chocolate chips, 1/4 cup of butter, and coffee granules (if using). Melt the mixture in the microwave, stirring at 20-30 second intervals until smooth. Allow it to cool slightly.
• In a separate microwave-safe bowl, heat 1/2 cup of heavy cream until it's steaming but not boiling. This should take about 45 seconds to 1 minute.
• Pour the hot cream over the melted chocolate and stir until well combined. Set this mixture aside to cool to room temperature.
• In a separate bowl, beat the remaining 1 cup of heavy cream with the sugar and vanilla extract until it forms stiff peaks.

Assembly

• Pour the chocolate mousse into the cooled Oreo crust.
• Refrigerate the pie for at least 2 hours or until the mousse is set.
• Before serving, top with whipped cream and garnish with grated chocolate or chocolate shavings.
• Slice and enjoy your luscious Chocolate Mousse Pie with Oreo Crust!