Preheat the oven to gas 6, 200°C, fan 180°C.
Peel and quarter the potatoes, then boil for about 20 minutes, until tender.
While the potatoes are cooking, melt 25g (1 oz) of the butter in a large pan and over a medium heat sauté the onions, carrots and garlic for about 10 minutes, until tender. Stir in the peas.
Add the lamb mince and cook until no longer pink. Add half the beef stock and cook, uncovered, over a low heat for 10 minutes, adding more stock as necessary to keep it moist.
Drain the potatoes and mash with the remaining butter and the milk. Place the lamb mixture in a baking dish. Layer the mashed potato on top. Rough up with a fork so there are peaks that will brown nicely.
Bake in the oven for about 30 minutes, until bubbling and brown. Place under the grill for the last few minutes to brown if necessary.
Recipe from Little Dish Favourites Cookbook Containing 70 foolproof recipes, including favourites from the award-winning Little Dish range, it makes cooking for your small children a pleasure. Find out more
Freezing and defrosting guidelines
Once the dish has cooled completely, transfer it to an airtight, freezer-safe container, seal and freeze for up to 1-3 months. To serve, defrost thoroughly in the fridge overnight before reheating. Loosely cover with foil and bake until dish is thoroughly heated through. Reheat until piping hot.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.