I use my Nana's recipe, which has never failed.
Mince in pan, cover with just enough very cold water to reach the top. Break down the mince into tiny bits, as small as you can in the cold water. Add onion, a small half teaspon of garlic, salt and pepper, then put to boil and if you want, a stock cube.
DON'T LET IT BOIL. As soon as it comes to the boil, turn off the heat and let it rest.
In the meantime, peel, chop small and cook a shedload of potatoes. About 700 gms. It is very important to use King Edward potatoes and nothing else. When the pots are done, mash them properly, with butter, milk (a Tablespoon) and cheese if you want.
Then layer, the meat, that has been rested, with enough juice to come up half the side of the dish you are using. Then, and this is the controversial thing, a layer of baked beans on top of the mince.
Then, the mash mix, that has to be smooth and creamy with the milk.
Bake in the oven until the stock at the bottom is bubbling.
Make gravy with the stock left after you took the mince out to avoid waste lol.
It results in a very nice, tender cottage pie with loads of flavour.