Preheat the oven to 190°C.
Bake the pricked potatoes for 1 to 1.5 hours until tender.
Simmer beef stock, red wine, and balsamic vinegar until reduced by half.
Sauté onions and carrots in olive oil until soft.
Brown the beef mince, stir in flour, and add the reduced liquid and bay leaf.
Simmer the meat mixture for 45 to 60 minutes and season.
Scoop out potato flesh and pass through a ricer.
Mix potatoes with butter and milk until smooth and creamy.
Spoon mince into a dish and pipe mash on top.
Bake at 190°C for 20 to 25 minutes until golden.
Serve the cottage pie with a side of boiled peas.