- 2 tablespoons olive oil
- 4 skinless, boneless chicken breasts (about 1 1/2 pounds)
- Kosher salt and freshly ground black pepper
- 2 small leeks, white and pale-green parts only, thinly sliced (about 1/2 cup)
- 1 small onion, minced (about 1/2 cup)
- 4 garlic cloves, minced
- 2 cups low-salt chicken broth
- 1 cup dry white wine
- 1/2 cup Dijon mustard
- 2 tablespoons minced fresh thyme plus thyme leaves for garnish
- 1 tablespoon unsalted butter
- Heat oil in a large heavy Dutch oven over medium-high heat. Season chicken breasts with salt and pepper. Place chicken in Dutch oven and cook until brown on both sides, 12-15 minutes total. Transfer to a plate and set aside.
- Place leeks and onion in same pot and sauté until tender, about 8 minutes. Add garlic and sauté until tender, about 2 minutes. Stir in broth, wine, Dijon mustard, and minced thyme and bring to a simmer. Return chicken to pot. Cover and simmer over medium-low heat until chicken is cooked through, about 15 minutes.
- Transfer chicken to plates. Bring liquid in pot to a boil; cook until sauce is thickened and glossy, about 15 minutes. Whisk in butter and season with salt and pepper. Spoon sauce over chicken and garnish with thyme leaves.