Preheat oven to 350 deg F. Spray an 8 x 8 inch baking dish and set aside. In a medium bowl, combine the graham cracker crumbs, melted butter, sugar, and lemon zest. Stir until well combined and mixture is moist. Press crumbs into 8x8 pan and bake for 10 minutes. Remove from oven and allow to cool at room temperature. Once the crust is cool, combine egg yolks and condensed milk until well mixed. Stir in lemon juice and zest. Stir until mixture begins to thicken. Gently fold in the raspberries. Fold carefully so you don't break them. Pour the filling evenly over the crust. Bake for 15 minutes or until just set. Cool to room temperature for 15 minutes. Melt the white chocolate in the microwave at 30 second intervals. take a fork or knife and drizzle the chocolate over the uncut bars. Refrigerate for at least 1 hour before serving. Cut into bars and serve. Keep bars in the fridge for up to 5 days.