Preheat the oven to 200°C.
Grease a medium ovenproof dish with butter and layer corned beef at the bottom.
Layer onions, thyme, and potatoes over the beef, seasoning each layer with salt and pepper.
Repeat the layering process, ensuring potatoes are the final top layer.
Pour chicken stock over the dish and dot the surface with the remaining butter.
Cover with foil and bake for 60 minutes until potatoes are tender.
Remove the foil and bake for another 15 minutes until the top is golden-brown.
Boil the runner beans in salted water for 2 to 3 minutes until tender.
Fry shallots in butter for 2 minutes until softened.
Add the boiled beans to the pan, fry for one minute, and toss with parsley and seasoning.
Serve the hotpot on plates with a side of runner beans.