Slice the briche loaf width-wise into ½ inch thick slices
Using a knife, generously spread some Nutella (or your spread of choice) on a slice of bread and sandwich it with another slice. Do the same with all the slices. Keep the sandwiched slices aside.
In a wide bowl, beat together the egg, vanilla extract, cinnamon powder and milk
Simultaneously, heat butter in a frying pan on low heat
Dip each sandwich into the egg mixture, coating it well and draining off the excess. Fry the coated bread in the pan, giving one side around 3 minutes to lightly brown and then flipping it over on the other side for another 3 minutes. Once all bread is done, keep the slices aside.
Make the sauce:
Add the water and sugar to a pot with high sides. Heat the pot on medium heat, until the sugar dissolves. Continue to heat on medium heat, as the liquid changes colour to amber (be careful, the caramel can overheat and turn dark). The caramel is ready now.
Gently, spoon out a couple of tablespoons of the caramel into a bowl. Working quickly, add the chopped walnuts to the bowl and quickly mix them into the caramel, before it sets. Keep the candied walnuts aside.
Turn off the heat in the pan, and add the butter carefully to the hot liquid. The mixture will foam. Whisk in the butter untill the mixture stops foaming. Finally, add in the Irish cream and whisk.
Once cool, pour over the french toast. Top with the candied walnuts and dust with confectioners sugar.