Preheat the oven to 160°C / gas 3 / fan 140°C. Grease a large shallow baking dish with a little bit of butter.
Cut the panettone into wedges and half again leaving the crust on. Butter each wedge and place in the dish buttered side up. place your stollen in between each slice.
In a jug whisk together the eggs, cream, milk, vanilla extract, orange zest and sugar and pour evenly over the panettone and stollen.
Place the dish in a roasting tin and pour hot water around it to the depth of about 2.5cm / 1 inch. Bake for 35 minutes until the pudding it just set.
Dust with icing sugar and serve with vanilla ice cream. Enjoy!