Creating a stunning Cranberry Mousse Pie involves a few straightforward steps. Follow these instructions closely for the best results:

1. Prepare the Crust:
– Preheat the oven to 350°F (175°C).
– In a bowl, combine graham cracker crumbs, melted butter, and granulated sugar.
– Press the mixture evenly into the bottom and up the sides of a 9-inch pie dish.
– Bake for 10-15 minutes, or until lightly golden. Let it cool completely.

2. Make the Cranberry Filling:
– In a saucepan, combine cranberries, sugar, water, and lemon juice.
– Cook over medium heat until the cranberries burst and the mixture comes to a boil.
– In a small bowl, mix cornstarch and cold water to create a slurry.
– Stir the slurry into the cranberry mixture and cook until thickened. Remove from heat and let cool.

3. Prepare the Mousse:
– In a mixing bowl, whip the heavy cream, powdered sugar, and vanilla extract until soft peaks form. Set aside.
– In another bowl, beat egg whites and cream of tartar until stiff peaks form.
– Gently fold the whipped cream into the egg whites until well combined.

4. Assemble the Pie:
– Spoon the cooled cranberry filling into the graham cracker crust, spreading it evenly.
– Top with the mousse mixture, smoothing it out to cover the cranberry layer completely.
– Refrigerate for at least 1 hour to allow the mousse to set.

5. Garnish and Serve:
– Once set, garnish with whipped cream, fresh cranberries, and lemon zest if desired.
– Cut into slices and serve chilled.

By following these steps, you will create an incredible Cranberry Mousse Pie that is sure to leave everyone asking for seconds!