Comforting cottage pie

Method

1. Preheat the oven to 180°C/fan160°C/gas 4. Heat the oil in a frying pan over a medium heat, add the onion, then sauté for 8-10 minutes until soft and translucent.
2. Add the mince and brown well, breaking the meat up with a wooden spoon. Add the tomato purée, mushroom ketchup, baked beans and a splash of water, then season to taste. Stir well, then bubble for 1-2 minutes.
3. Transfer to a 1 litre ovenproof dish. Carefully top with the mashed potato, then dot with the garlic butter. Cook in the oven for 30 minutes until browned and crisp on top and bubbling around the edges.