Preheat your oven to 170C. Take a jug and mix the eggs, cream, vanilla extract, light brown sugar and cinnamon. Put to one side.
Take your bread, and spread two of the pieces with Nutella and two of the pieces with the caramel sauce. Sandwich the Nutella piece with the caramel piece (so both of the fillings are on the inside). Repeat with the other two pieces. Cut each sandwich into four triangles, so you have 8 altogether.
Take a medium sized deep baking dish (mine is about 15cmx22cm and 6cm deep) and arrange the triangles upright in the tin. I alternated crust side up and crust side down.
Pour the egg/cream mixture all over the bread, and sprinkle the Demerara sugar on top. Place in the oven and cook for 30 minutes. Keep an eye on the pudding for the last 10 minutes to ensure the bread doesn't burn. You could place some foil on top if it's going too dark.
Take out of the oven and serve on it's own or with ice cream or custard (and maybe an extra spoonful of caramel if you like).