Heat 1 tablespoon olive oil in a Dutch oven or a large pan over medium-high heat and add the chicken. Season with 1/4 teaspoon salt and 1/4 teaspoon pepper. Saute until chicken is no longer pink outside, about 5 minutes. Remove chicken from pan and set aside.
In the same pan, heat the remaining olive oil. Add the onion, leek, celery, thyme, and rosemary and cook, stirring often, until softened (about 5 minutes). Stir in garlic and cook for 1 minute to soften. Add the mushrooms and cook, stirring occasionally, until softened and any liquid is released, about 5-6 minutes. Add the red wine, tomato paste, Worcestershire sauce and chicken along with any accumulated juices to the pan.
Bring to a boil, then reduce heat to low. Cover and cook, stirring once or twice, until the chicken is tender, about 10 minutes. Taste and add more salt or pepper, if desired.
Meanwhile, mix cornstarch and water in a small bowl. Stir the mixture into the stew and cook until thickened, about 2-3 minutes. Remove from heat. Garnish with parsley and serve with boiled potatoes or rice.