In a medium bowl, combine graham cracker crumbs with melted unsalted butter until evenly mixed. Reserve half for layering and press the rest into the bottom of your dish.

In a well-chilled mixing bowl, pour in heavy whipping cream and beat with an electric mixer on medium speed until stiff peaks form, about 3-5 minutes.

In another bowl, beat cream cheese until smooth. Gradually add powdered sugar, key lime juice, lime zest, and vanilla extract. Mix until creamy.

Gently fold the whipped cream into the cream cheese mixture until fully incorporated.

Layer half of the cream filling over the crust. Sprinkle reserved crumbs over this layer, then add remaining filling on top.

Cover with plastic wrap and refrigerate for at least 2 hours before serving.