In a medium bowl, whisk together 1 cup of heavy whipping cream, 1 cup of sweetened condensed milk, and ½ cup of fresh key lime juice until luxuriously smooth, about 2-3 minutes.

Melt 1 cup of white chocolate chips in a microwave-safe bowl in 30-second bursts, stirring until smooth, about 1-2 minutes.

Stir in 2 tablespoons of softened unsalted butter and the zest of 1 lime into the melted chocolate until fully incorporated.

Gradually pour the creamy key lime mixture into the melted chocolate, stirring continuously until thoroughly blended, about 1-2 minutes.

Fold in 1 cup of crushed graham crackers until evenly distributed throughout the mixture.

Cover the bowl with plastic wrap and refrigerate for at least 2 hours, or until firm enough to handle.

Scoop out about 1 tablespoon of the mixture and roll it into a smooth ball, placing each truffle on a parchment-lined baking sheet.

If desired, melt additional white chocolate for dipping or roll truffles in extra graham cracker crumbs or shredded coconut.