I have an old recipe titled Minced Chicken. It's a casserole type dish. It says to use 1 hen, cooked and minced. What type of hen is this referring to? I found a cornish hen at the store but it was small, I didn't feel that this was the right type to use.
I suspect what's meant by hen, as opposed to chicken, is a laying hen. When a laying hen's egg production slows down, usually between 3 to 5 years in backyard chicken farming, they're killed and used as 'stewing hens'. Commercial layers are generally culled earlier between 1 to 2 years.
You definitely don't want a Cornish hen. In North America, they're simply whole broilers (usually 7-10 week old birds) - nothing else. Older stewing hens make the best soups, stews and casseroles as the flavour is stronger and the method of moist slower cooking tenderize the tougher meat.
If it's an "old recipe", you want a hen that has spent its life running around out of doors, finding its own food, and building up muscle rather than fat. After several hours in a casserole, the meat will actually taste of something, not just look like chicken.
You won't that sort of poultry in a food store, but if you can find an organic farmer or a private individual who keep a few hens, you might be more lucky.
Commercial egg producers are more likely to offload their old hens to a company that turns them into pet food, or produces "mechanically recovered meat" for the processed food industry, not something that still looks like a complete chicken when you buy it!