Make the filling – In a large bowl, beat the cream cheese until smooth. Mix in the sweetened condensed milk, key lime juice, vanilla, and lime zest. In a separate bowl, whip the heavy cream to stiff peaks, then gently fold it into the lime mixture.

Layer it up – In an 8×8-inch dish, spread a thin layer of the filling on the bottom. Add a single layer of graham crackers and then a layer of whipped cream. Repeat the layers until you run out of filling, ending with a creamy layer on top.

Chill – Cover and refrigerate for at least 4 hours (overnight is even better!) to let the flavors meld and the crackers soften into a cake-like texture.

Garnish & serve – Spread extra whipped cream on top, sprinkle with lime zest, and decorate with lime slices. Slice, serve, and enjoy the creamy citrusy goodness!