Preheat oven to 200 degrees Celsius.
Heat a wok on medium and spray with 1 kcal spray.
Add the onion and garlic and sweat for a minute or two.
Add in the mince cooking until brown.
Add in the mushrooms and frozen peas.
Pour in the stock and bring to a simmer for about 5 minutes to let it reduce slightly.
Season with salt, parsley and thyme.
Add in the Worcestershire sauce.
Meanwhile to make the mash topping, add the carrots and sweet potatoes to a separate pot and fill with cold water. Bring to the boil and simmer for about 10 minutes or until both the carrots and sweet potatoes are tender.
Drain the carrots and sweet potatoes. Add in about 100ml of hot milk and begin mashing until you have a smooth creamy consistency.
Season the mash with salt, pepper and rosemary.
Pour the mince mixture into a large pie dish.
Spoon the mash over the mince mixture and spread evenly with a fork.
Spray with 1 kcal spray.
Bake for 20 minutes until the top is starting to colour and the mince is bubbling at the edges. Flash under the grill to brown if you like!