Finely chop the white chocolate and place in a heatproof bowl. Set aside.

Add lemon zest to cream in a small heavy saucepan and bring to a simmer, taking care not to boil. Remove from heat.

Add butter and salt to white chocolate, then pour hot cream mixture into bowl. Melt over a saucepan with simmering water until smooth (do not allow water to touch glass bowl). Add lemon juice and stir to combine. Chill mixture for at least 4 hours.

Using a teaspoon or a small cookie scoop portion out 1 inch balls of ganache mixture. Roll in your hands to form a ball (quickly, as it will begin to melt from the heat of your hands).

Immediately sprinkle each truffle with the sanding sugar and place on a parchment lined baking sheet.

Allow to set for at least 5 minutes before serving (will keep for up to two weeks when stored in an airtight container).