Cut the Swiss roll into 1/2-inch slices and line the sides and base of your bowl with them.
Roughly chop the muffins and place half of the muffin chunks in the center of the bowl.
Top with half of the chocolate custard or chocolate pudding.
Whisk the heavy cream until soft peaks form and spoon half of it over the custard.
Top with the remaining chocolate muffin chunks, followed by the remaining custard.
Spoon the remaining cream on top and smooth it out so that it covers the whole of the top of the trifle.
Spoon the Nutella on top of the cream in 8-10 little dollops around the edges of the trifle. Use a toothpick to swirl the Nutella into the cream.
Break the chocolate caramel pieces up and scatter them on top of the trifle in the middle.
Either serve immediately or cover and refrigerate for up to a day before serving.