Hi, i get asked to make triffle for xmas every year for about the last 10 years.
Here we go.
layer in a deep bowl - like maybe a salad bowl.
sliced jam roll cake
a tin of sliced peaches, with some juice on the jam roll (or any alcahol such as schnaps or sherry etc)
one packet of raspberry or port wine jelly already set and chopped up.
600 mls of custard, i make my own with milk and custard powder on the stove top, but you can just use the carton stuff.
top with thickened cream whipped.
keep in the fridge overnight so it kind of sets.
You can just adjust the ingredient quanitites to suit or you can stretch it out if making for a lot of people by using like a lasagne style dish also works well.