The CWI Cookbook

 Cold roast beef, minced
Chopped onion
Pepper and salt
Beef stock, bouillon or gravy
Mashed potatoes
Butter

Mince cold roast beef, fat and lean, very fine, add chopped onion, pepper, salt and a little good gravy, fill scollop shells two parts full, and fill them up with potatos mashed smooth with cream, put a bit of butter on the top, and set them in an oven to brown.

From The Virginia Housewife or, Methodical Cook, by Mary Randolph,1824

Comment: This is essentially a cross between roast beef hash and Shepherd’s Pie. It is unclear whether Mrs. Randolph wants these cooked in the actual shells of scallops, presumably preserved after an earlier meal of the bivalves, or if there was a metal baking tin of the same name and general shape on the market. A tart pan, pie pan, or similar vessel would probably serve, as would scallop, oyster or similar shells should you have any lying about.