A layered trifle dessert may look difficult and involved, but this one is actually quite easy, especially when you consider the make-ahead components. The custard needs to chill at least hours, so make that up to a day in advance; stir in the buttermilk right before using. You can also make the White Chocolate-Buttermilk Cake a day or two in advance and keep covered until you are ready to assemble the trifle. Use a clear glass trifle dish to show off all the delicious components of this recipe. The striking color combination of navel oranges and the bright red blood oranges give this dish extra visual appeal.