Prepare the Ganache:

In a heatproof bowl, combine the chopped white chocolate, heavy cream, lemon zest, lemon juice, and softened butter.

Melt the Mixture:

Place the bowl over a saucepan of simmering water (double boiler method).

Stir continuously until the mixture is smooth and fully melted.

Remove from heat and let it cool slightly.

Chill the Ganache:

Cover the mixture and refrigerate for about 2 hours, or until it becomes firm enough to handle.

Form the Truffles:

Using a melon baller or teaspoon, scoop small amounts of the chilled ganache and roll them into balls between your palms.

Coat the Truffles:

Roll each truffle in powdered sugar until fully coated.

Serve:

Place the truffles on a baking sheet lined with parchment paper.

Refrigerate for an additional 30 minutes to set before serving.