In a mixing bowl, combine the graham cracker crumbs and melted butter until fully coated. Reserve 1/2 cup for later.

Press the crumb mixture into the bottom of the trifle dish evenly.

Chill a mixing bowl and whisk, then whip heavy cream until stiff peaks form, about 2-3 minutes.

In another bowl, beat the cream cheese until smooth. Add powdered sugar, key lime juice, zest, and vanilla, mixing until creamy.

Gently fold the whipped cream into the cream cheese mixture until combined.

Layer half of the key lime filling over the crust, top with reserved crumbs, then add the remaining filling.

Top with remaining graham cracker crumbs and additional lime zest if desired. Cover and refrigerate for at least 2 hours.