Melt 1 pound white chocolate, butter and heavy cream together in a microwave-safe bowl on medium heat, stirring every 30 seconds until smooth.
Stir in salt, lemon juice and zest.
Refrigerate mixture until firm.
Use a small scoop or melon-baller to scoop out truffle centers. Roll into balls and chill again until firm.
Melt remaining white chocolate and use to coat centers, dipping them with a truffle fork or small spoon.
Let truffles harden on a cooling rack and decorate if desired. 2-3 dozen truffles, depending on size.