Heat the vegetable oil in a deep ovenproof pan. Fry the bacon for 3-4 minutes, or until golden-brown and slightly crisp. Remove from the pan and set aside to drain on kitchen paper.
In the same pan used to cook the bacon, arrange a layer of the sliced potatoes in the bottom of the pan. Cover the potatoes with a layer of sliced onions, then a layer of sliced carrots. Layer over some of the crisp bacon, then season with salt and freshly ground black pepper.
Repeat the process with the remaining potatoes, onions, carrots and bacon, finishing with a layer of potatoes on top. Season with salt and freshly ground black pepper.
Pour in the chicken stock so that all of the ingredients are covered, then bring to the boil. Cover the pan with a lid and reduce the heat to a simmer. Simmer for 15-25 minutes, or until the potatoes and carrots are tender.
Preheat the grill to high.
Uncover the pan and sprinkle over the grated cheese. Grill for 5-6 minutes, or until the cheese is bubbling and golden-brown.
To serve, spoon the panhaggerty into bowls and serve with some crusty bread to mop up the juices.