Begin by crushing the graham crackers into fine crumbs, using a food processor or a rolling pin.

In a mixing bowl, combine the crumbs with melted unsalted butter until they are fully moistened and resemble wet sand.

Press this mixture firmly into the bottom of a trifle dish or individual serving cups to create an even layer.

In a separate mixing bowl, beat together the softened cream cheese and powdered sugar until smooth and creamy.

Gradually add in the cold heavy cream, key lime juice, and key lime zest, and whip until fluffy.

Spread half of the creamy lime filling over the crust layer and smooth it out evenly.

Add another layer of the graham cracker crumbs, followed by the remaining filling, and top with the last of the crumb mixture.

Cover the trifle with plastic wrap and chill in the refrigerator for at least 2 to 3 hours.

Before serving, add a dollop of additional whipped cream on top and sprinkle with extra key lime zest.