When the leaves begin to turn brown and the evenings get darker, simple, hearty casseroles like cottage pie start to grace supper tables. Originally a way to use up scraps of meat leftover from a previous meal, cottage pie is now more commonly made with ground meat, but sometimes made with braised. The most distinguishable feature of cottage pie is the mashed potato crust, baked until golden and crisp.
The terms "cottage pie" and "shepherd's pie" were once used interchangeably, whether or not the meat used was beef or lamb. Now cottage pie refers specifically to beef, whereas shepherd's pie refers to the use of ground lamb. This version of cottage pie uses shallots and sherry to add a slightly sweeter, savory note to the dish. It's a personal preference to use the peas as a layer between the meat and potatoes, but feel free to fold them into the meat—or use whatever technique your Mum used when you were a kid.