Bring salted water to a boil. Wash, peel and cube the potatoes.
Blanch haricot verts in salted water for a few minutes, then reserve.
Simmer potatoes in the same pot for about 30 minutes, or until tender. In the meantime, wash and cut the carrot and onion.
Reserve potatoes and allow to cool. Clean the pan, and brown the beef.
Stir in the carrot and onion, and continue to cook until fragrant.
Add Worcestershire sauce, Better than Bouillon, and a bit of water. Taste and adjust, then simmer uncovered for about 15 minutes.
In the meantime, mash the potatoes and mix in half of the cheese. Season mashed potatoes. Preheat the oven to 200c/400F
Once the meat mixture is done, pour it into the baking tray. Spoon mashed potatoes on top and smooth it out.
Top the mashed potatoes with the rest of the cheese, and bake for about 20 minutes or until the cheese is browned.
Allow to cool for about 20 minutes before slicing and serving.