In the same pot add more oil, if needed, and saute the onions, carrot and celery until tender. Add cayenne pepper and tomato paste and cook until tomatoes turn a deep reddish brown color. Add flour and stir until incorporated then pour in reserved marinade. Stir and simmer until thickened about 10 minutes. Add chicken back to the pot and pour in enough stock to just come up the sides of the chicken but not cover it completely. Bring to a boil, then lower to a simmer and cook covered for about 1 hour or until the chicken falls off the bone.
Gently remove legs from pot and strain liquid from the solids, discarding the solids. Return chicken and strained liquid back to the Dutch oven and bring to a simmer. Heat a large saute pan with remaining 2 tablespoons oil over medium-high heat and add bacon. Cook until crispy then add mushrooms and pearl onions. Continue to cook until tender and browned. Add mixture back to the pot with the chicken. Toss the noodles with butter. Place the noodles on a serving platter or individual plates and top with the chicken. Garnish with chopped parsley and serve.