Preheat the oven to 425˚F.
To spatchcock the chicken, turn it breast-side down on a cutting board.
Using sharp kitchen shears and starting at the cavity end, cut along one side of the spine, then the other side, and remove it. (It can be used to make stock, if you like.)
Open the bird like a book, flip it over and flatten it, pressing down on the breast and turning the legs so that they lie flat as well.
Pat the skin dry with paper towel, rub it all over with oil, sprinkle with salt and pepper (and your choice of herbs or a spice rub, if you like).
Roast for 30-40 minutes, until the juices run clear and legs wiggle easily in their sockets.
If you like, while the chicken rests for 5 minutes, tear the kale leaves (discard the stems) over the hot roasting pan, stir them around to coat with the residual oil and chicken drippings, and return to the oven for 5 minutes, or until crisp and golden.
Crush and sprinkle over or serve with the roasted chicken.