Line an 8x8 square pan with parchment paper
Melt white chocolate and butter in the microwave or over a double boiler. Once chocolate is smooth and glossy, pour into the base of the pan creating an even layer. Chill in the fridge
For the graham layer; in a saucepan over medium heat melt butter. Once melted, remove from heat and add in sugar. Gradually whisk in egg and then return to heat constantly stirring until the mixture thickens (1-2 minutes). Remove from heat and add in graham crumbs, coconut and chopped nuts. Press the mixture evenly on top of the chocolate layer, and return to fridge until firm.
Prepare the Lemon pie filling according to the package. Once cooled, pour the lemon filling over the graham layer and return to the fridge to set for approximately an hour.