Prepare the Crust: In a mixing bowl, combine 1 cup of graham cracker crumbs with 4 tablespoons of melted unsalted butter. Press the crumbs into the bottom of a trifle dish to form a solid crust.

Whip the Cream: In a separate chilled mixing bowl, whip 2 cups of heavy whipping cream until stiff peaks form, about 3–5 minutes.

Mix the Filling: Beat 8 ounces of softened cream cheese until smooth, then gradually add ½ cup of powdered sugar, ½ cup of key lime juice, 1 tablespoon of key lime zest, and 1 teaspoon of vanilla extract.

Fold in Whipped Cream: Gently fold the whipped cream into the cream cheese mixture, maintaining its airy texture.

Assemble the Trifle: Spread half of the lime filling over the crust, sprinkle with reserved graham cracker crumbs, and top with the remaining lime filling.

Chill the Dessert: Cover and refrigerate the trifle for at least 2 hours.

Serve and Enjoy: Garnish with extra graham cracker crumbs and lime zest before serving.