Prepare the hens: Remove the dark meat from the legs and chop it very finely. Lay the main part of the bird flat, skin side down. There will be a rough rectangle of skin with the two breasts and their smaller fillets attached at the top. Remove one small fillet and lay it between the breasts to fill the indentation. Use the other to fill any other gaps. Lay a piece of plastic over top, and pound the whole flat. Remove the plastic. Push the meat around a little, if you need to, to achieve and even square of white meat, roughly centered on the skin. Season with salt and pepper.
Make the stuffing: Heat 3 tablespoons of the butter and sauté the onion until soft. Add the garlic one minute. Remove to a bowl. Heat the remaining butter in the pan and toast the breadcrumbs. Add them to the onions. Stir in the figs, Cognac, and thyme. Season with salt and pepper.
Heat the oven to 325°F/160°C. Lay the bacon slices, slightly overlapping, on a piece of foil. Lay the bird on top, and season with salt and pepper. Spread over the stuffing, then roll into a log. Wrap in foil, twisting the ends to make a tight cylinder. Bake 30 minutes. Remove the foil and return to the oven 10 minutes longer. Remove. Let rest 10 minutes before slicing to serve with watercress salad.