Prepare a double base pan and heat it up. Place the seasoned lab and seal it on both sides for 3 minutes. Remove and leave to rest on a draining tray, place the sausage and cook for 4 minutes. In another pot, put the diced potatoes and pour the milk and cream together with the crushed garlic. Bring to the boil and simmer for about 15 minutes until the potato is soft and the milk is nearly evaporated. Place the potatoes in a sieve and drain excess liquid, mash it with a fork or potato masher. Add 25g of butter, salt and pepper and cover with cling film to keep warm. Boil 50ml of cream with some salt and pepper, add the peas from frozen and blend everything together to get a smooth puree. Place the lamb in an ovenproof dish and put in a pre-heated oven and continue cooking for about 12 minutes. Assemble the dish to your liking.