Season chicken all over with 1 teaspoon salt and the pepper. Pat again to keep surfaces dry.
Heat olive oil and butter in a large Dutch oven over medium-high heat.
Sear chicken skin-side down until deep golden, 6–8 minutes. Flip and brown 3–4 minutes more. Transfer to a plate.
Add mushrooms and cook until browned and their liquid evaporates, about 5 minutes. Scoop out and reserve.
Soften onion, carrots, and celery in the pot over medium heat, 4–5 minutes. Stir in garlic for 30 seconds.
Sprinkle flour over vegetables and cook, stirring, 1 minute to remove raw taste.
Pour in white wine and scrape up browned bits. Simmer until slightly reduced, about 2 minutes.
Stir in broth, thyme, and remaining 1/2 teaspoon salt. Return chicken to the pot, skin-side up.
Cover and simmer gently until chicken is tender and cooked through, 20–25 minutes.
Uncover. Stir in cream, Dijon, lemon juice, browned mushrooms, and peas. Simmer 3–4 minutes to thicken.
Taste and adjust salt. Finish with parsley and serve hot.
Notes
Try swapping half the cream for crème fraîche for a slight tang. Serve over buttered egg noodles, rice, or mashed potatoes. Leftovers keep 3 days in the fridge; reheat gently with a splash of broth.This recipe is an original creation inspired by classic Classic Chicken Fricassee Made Easy flavors. All ingredient ratios and instructions are independently developed.