Prepare the mash. Cook the potatoes in a pot of boiling water until fork tender. Drain then mash. Add in the butter, milk and parmesan. Mix well until combined.
In a pan over medium heat with a bit of olive oil, brown your ground beef mince.
Add the chopped up onion, carrot, celery, garlic and mushroom into the pan and saute for around 10 minutes.
Add in the flour and stir so that everything is coated in the flour evenly. Cook the flour for 2 minutes.
Add in the tomato paste, worcestershire sauce and red wine. Scrap what's stuck on the bottom of the pan and let the wine reduce.
Add in the stock and rosemary and simmer until the sauce is nice and thick (mine took around 20 minutes), stir occasionally . Then remove the rosemary sprig and season to taste. Meanwhile preheat the oven to 200C/400F.
Transfer the mince over to a baking dish then top with the potato mash. Create a pattern on top of the mash if you want then bake for 20-30 minutes or until the top of the mash is golden and crispy.