Place the white chocolate chips in a medium mixing bowl and set them aside. n a small saucepan, melt the butter with the lemon zest. Stir in the heavy cream and scald (bring just before boiling) the mixture.
Pour the cream mixture through a fine-mesh sieve over the white chocolate chips. Add the lemon extract and optional food coloring, then stir until the mixture is smooth.
Cover and refrigerate the chocolate chip mixture until the mixture is firm enough to handle, about 30 minutes.
Scoop heaping teaspoonfuls of the chocolate chip mixture and form into balls. Roll the balls in the powdered sugar. Refrigerate the truffles for at least 30 minutes before enjoying them.