Prepare 8x8 pan by lining with aluminum foil, foil up the sides as well.
Prepare white chocolate shavings in a shallow dish
Prepare a cookie sheet line with parchment to place the finished truffles on to set
Put chopped semi-sweet chocolate in a heat proof bowl.
Heat heavy cream to boil
Pour heavy cream over chocolate, let sit for 1 minute, then stir in small circular motions until completely mixed.
Add in Grand Marnier and lemon zest. Stir to combine well. Store in cool dark place to cool and firm up over night.
When ready take the ganach brick out of the pan onto a cutting surface and cut into equal squares (I cut 7 strips down and 7 strips across which provided 49 squares/small truffles).
Run hands under cold water and dry. (you will probably have to do this after every third truffle)
Take one ganache square and pinch in the corners (this will make it easier to roll) and roll into ball. Immediately roll in shave white chocolate and put on cookie sheet to set.
Repeat until done.
Store in a cool dark place until ready to serve. Can be kept in air tight container for up to 4 days.