Spatchcock is a variant of spitcock, a term used for grilled split eel. It’s similar to the term butterfly, though spatchcock refers only to fowl, whereas butterflying typically applies to boneless cuts (meat, poultry, fish and so on). Spatchcocked birds cook up well with crisp skin and juicy meat, but there’s always some smart ass who’s going to tell you it looks like that chicken didn’t make it across the road.
Preheat oven to broil. Rinse hen, pat dry, remove wing tips and backbone with shears or a knife then turn the hen breast side up, open it up like a book and then whack it a time or two with the heel of your hand (you can use your fist if you like) to crack the breastbone and flatten it out. Tuck the wings under the thighs. Oil the hen, season with salt and pepper. Place rosemary, garlic and whatever other herbs you might like in the bottom of a skillet, lay the bird on top, and cook until browned and sizzling.