Pat your chicken with paper towel and season both sides with salt and pepper. Add oil into a large skillet over medium high heat. Add your chicken and brown on both sides. Remove and place on a platter.
Into the same pan, add the pearl onions and brown on all sides and reserve with the chicken.
Add more oil if needed and add your mushrooms and saute for a couple of minutes. Add the onions garlic, turn heat down to medium and stir occasionally. Cook for about 4-5 minutes or un just translucent.
Add the flour and stir in and cook for a minute. Add the wine, stir to deglaze the pan.
Add the milk, bay leaves, thyme, chicken pieces (skin side up), pearl onions and enough stock to almost cover the chicken. Add lettuce, bring up to a simmer and place the lid on (slightly ajar).
Simmer for 30 minutes then remove lid and simmer for about another 10 minutes or until sauce has thickened.
Turn off heat, taste and add salt and pepper to taste. Garnish with chopped fresh parsley and served on top of garlic mashed potatoes. Variation: You can use baby spinach instead of romaine lettuce but add it at the end as they wilt very easily.