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

Melt the unsalted butter in a microwave-safe bowl, then mix it with the crumbs until evenly coated.

Firmly press this mixture into the base of a trifle dish or individual serving cups.

In a large mixing bowl, beat the softened cream cheese and powdered sugar together using an electric mixer on medium speed until smooth and creamy.

Gradually add the cold heavy cream, key lime juice, and the zest of key limes, continuing to blend until the mixture is fluffy and has formed soft peaks, about 3-5 minutes.

Spread half of the fluffy filling over the crust, ensuring even coverage.

Add a layer of additional graham cracker crumbs for added texture, followed by the remaining filling.

Finish with another generous layer of crumbs on top.

Cover the assembled trifle with plastic wrap and refrigerate for 2-3 hours.

Garnish with freshly whipped cream on top and sprinkle additional key lime zest before serving.