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

In a microwave-safe bowl, add 1 cup of white chocolate chips. Microwave in 30-second intervals, stirring in between until fully melted and smooth, about 1-2 minutes total.

Once the white chocolate is melted, add ½ cup of softened unsalted butter and the zest of 2 limes. Stir until creamy, then gently fold in the prepared whipping cream mixture.

Gradually add 1 cup of finely crushed graham crackers to the truffle mixture and fold gently to evenly distribute the crumbs.

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

Use a cookie scoop or hands to roll the mixture into 1-inch balls and place on a lined baking sheet.

Optionally roll the truffles in extra graham cracker crumbs or dip in melted white chocolate, then let set on the parchment-lined sheet.