Start by whisking together the eggs, milk and rum. Then add the cinnamon and sugar to combine fully.
Pour into a baking dish and add the bread, continue to turn every 10 mins for 30 mins.
Reduce the cider by about half until syrupy for a hint of zing, then whisk in 100g of the butter a little at a time. Add in the vinegar and take off the heat. Next, add in the apple for a touch of sweetness and then mix well.
Melt the rest of the butter in a frying pan and shake off any excess liquid from the bread. Cook for 3-5 mins each side. Now bake at 160c for 12-15 mins until crispy.
Beat together the mascarpone, vanilla and cream until fluffy and fully combined.
Serve the bread, apples, sauce and cream. Top with toasted chopped hazelnuts for some added crunch and enjoy!