First, generously butter the slices of bread on one side, then spread the marmalade on 3 of these slices, and put the other 3 slices on top (buttered side down) so you've got 3 rounds of sandwiches.
Now spread some butter over the top slice of each sandwich and cut each one into quarters to make little triangles or squares.
Then arrange the sandwiches, butter side up, overlapping each other in the baking dish and standing almost upright.
After that, whisk the milk, cream, eggs and sugar together and pour this all over the bread.
Scatter the surface of the bread with the grated orange zest, demerara sugar and candied peel, then place the pudding on a high shelf and bake it for 35-40 minutes until it's puffy and golden and the top crust is crunchy.
Serve the pudding straight from the oven while it's still puffy, with either crème fraîche or chilled pouring cream.
