Prepare the barbecue for indirect cooking over medium-low heat (170°C to 190°C).] If you are using a Weber Q barbecue, set up your barbecue with a convection tray and trivet.
Beat the eggs with 1 tablespoon of the sugar, the vanilla, and milk. Strain the mixture into a lightly buttered aluminium drip pan. Add the sultanas and walnuts.
Butter the slices of bread. Cut the buttered bread into triangles and float them on top of the egg and milk mixture. Sprinkle the pudding with the remaining 1 teaspoon sugar and the cinnamon.
Bake the pudding over indirect medium-low heat, with the lid closed, for 30 to 40 minutes, or until the custard is set.
Bake the pudding over medium-low heat, with the lid closed, for 30 to 40 minutes, or until the custard is set.