Turn the oven on and set the heat to 450 degrees.
Put the skillet or Dutch oven on the stove and set the heat to medium. When it is hot, add the chicken legs. (Be very careful: the hot oil might spatter.)
Cook, without stirring, for 5 minutes, then use the tongs or spatula to carefully turn the legs over. Cook again, without stirring, another 5 minutes.
Turn off the heat, take the chicken legs out, and put them on a plate (don’t worry if some of the skin is stuck in the pan).
Reheat the pot over medium heat and add the onions, garlic, carrots, celery, sausages, thyme, bay leaves, and salt, and cook, stirring occasionally, until the onions have turned a nice golden color, about 30 minutes.
Add the beans, tomatoes, and chicken broth; stir well. Bring the mixture to a boil, then turn off the heat and use tongs to carefully nestle the chicken legs in the bean mixture. Once the oven temperature has reached 450 degrees, put the pot in the oven and cook uncovered for 30 minutes.
Meanwhile, put the bread crumbs, parsley, and remaining tablespoon of oil in the bowl and mix well. Take the pot out of the oven, sprinkle the bread crumb mixture over it, then put the pot back in the oven and bake until the bread crumbs are browned, about 15 minutes.
Set aside for 10 minutes and serve. Or transfer to a container, cover and refrigerate up to 2 days.