Rub the suprêmes with drops of lemon juice and sprinkle lightly with salt and pepper. Heat the butter in the casserole until it is foaming. Quickly roll the suprêmes in the butter, lay the buttered paper over them, cover casserole and place in hot oven. After 6 minutes, press top of suprêmes with your finger. If still soft, return to oven for a moment or two. When the meat is springy to the touch it is done. Remove the suprêmes to a warm platter and cover while making the sauce (2 to 3 minutes).