In a large mixing bowl, beat the softened cream cheese with an electric mixer until smooth and creamy.
Gradually add the powdered sugar, mixing until well combined and fluffy.
Add the sour cream, key lime juice, vanilla extract, and salt. Mix until the mixture is smooth and well incorporated.
Transfer the dip to a serving bowl and sprinkle graham cracker crumbs on top for garnish.
Chill the dip in the refrigerator for at least 30 minutes before serving to allow the flavors to meld.
Serve with additional graham crackers, fruit, or pretzels for dipping. Optionally, garnish with lime wedges and a dollop of fresh whipped cream.