Preheat your oven to 350°F (175°C). Grease the bottom and sides of a 9-inch pie pan or springform pan to prevent the crust from sticking. If you prefer, you can line the bottom of the pan with parchment paper for easier removal later. Preheating the oven will ensure the crust bakes evenly and crisps up perfectly.
In a medium bowl, combine the graham cracker crumbs, granulated sugar, and liquefied unsalted butter. Stir until all the crumbs are coated in butter and the mixture resembles wet sand. The butter helps bind the crumbs together while also adding a rich flavor, and the sugar will enhance the crust’s sweetness. You should be able to press the mixture into the pan without it crumbling apart.
Pour the graham cracker mixture into the prepared pie pan and press it down evenly along the bottom and slightly up the sides. Use the back of a spoon or the bottom of a measuring cup to press the crumbs firmly into the pan, ensuring a compact and even crust. This helps the crust hold its shape after baking.
Bake the crust in the preheated oven for 8 to 10 minutes or until the crust is golden brown and firm. Keep an eye on it during the last couple of minutes to avoid burning the edges. Once done, remove the crust from the oven and let it cool completely while you prepare the mousse filling.
For the mousse filling, start by heating 3/4 cup of the heavy whipping cream in a small saucepan over medium heat. Heat it until it’s just about to simmer, but do not let it boil. Meanwhile, finely chop the white chocolate to ensure it melts quickly and smoothly when added to the hot cream. The white chocolate should be finely chopped to facilitate a smooth melt without clumps.
Once the cream is heated, pour it over the chopped white chocolate in a heatproof bowl. Let it sit for about 1-2 minutes to soften the chocolate, then stir until the mixture is smooth and fully combined. The white chocolate should melt completely, creating a smooth, creamy mixture. Allow the chocolate mixture to cool to room temperature, stirring occasionally to help it cool more evenly.
In a separate large mixing bowl, beat the softened cream cheese with an electric mixer on medium speed until smooth and creamy. This step is crucial to avoid any lumps in the mousse filling. After the cream cheese is smooth, gradually add the cooled white chocolate mixture, beating well until fully incorporated. This will create a smooth, creamy base for the mousse.
In a separate mixing bowl, beat the remaining 3/4 cup of heavy whipping cream until stiff peaks form. Be careful not to overwhip the cream, as it could turn grainy. The whipped cream should hold firm peaks when you lift the beaters from the bowl, but not be overly dry. Gently fold the whipped cream into the white chocolate mixture in stages, using a spatula. Folding the whipped cream helps maintain the light, airy texture of the mousse.
Once the whipped cream is fully incorporated, add the peppermint extract and gently fold it in until evenly distributed. The peppermint extract will add a refreshing minty flavor that perfectly complements the sweetness of the white chocolate. Taste the mixture at this stage to see if you’d like to add a little more peppermint extract for a stronger flavor, but be cautious, as the extract can be potent.
Pour the mousse filling into the cooled graham cracker crust, smoothing the top with a spatula. Gently tap the pan on the counter to help remove any air bubbles and ensure the mousse settles evenly. Refrigerate the pie for at least 4 hours, or until it is set and firm enough to hold its shape when sliced. For the best results, let the pie chill overnight to fully set and develop the flavors.
