In a medium bowl, combine 1 cup of graham cracker crumbs with 4 tablespoons of melted unsalted butter. Mix until the crumbs resemble wet sand. Reserve ½ cup for layering and topping.

Press the crumb mixture firmly into the bottom of a trifle dish to create a solid base.

Chill your mixing bowl and beaters in the freezer for about 10 minutes. Beat 2 cups of heavy whipping cream until stiff peaks form, about 2-4 minutes.

In a separate bowl, beat 8 ounces of softened cream cheese until smooth. Gradually add ½ cup of powdered sugar, ½ cup of key lime juice, 1 tablespoon of lime zest, and 1 teaspoon of vanilla extract. Mix until creamy.

Gently fold the whipped cream into the cream cheese mixture until just combined and fluffy.

Spread half of the creamy lime filling over the crumb base. Sprinkle reserved graham cracker crumbs over the filling. Layer remaining filling on top and finish with a sprinkle of crumbs.

Cover with plastic wrap and refrigerate for at least 2 hours to set.