Pat chicken dry, and sprinkle with 1 teaspoon of the salt and 1⁄2 teaspoon of the pepper. Place flour in a large ziplock plastic freezer bag; add chicken to bag. Seal bag, and toss to coat with flour. Heat oil in a 12-inch cast-iron skillet over medium-high. Remove chicken from bag, reserving flour in bag. Shake excess flour mixture from chicken, and place, bone side up, in skillet. Cook chicken until deep golden brown, 4 to 5 minutes per side. Remove chicken to a plate, and keep warm.

Add mushrooms to hot drippings in skillet; cook, stirring often, until beginning to brown, about 4 minutes. Add carrots and leek; cook about 3 minutes. Add 2 tablespoons of the reserved flour; cook, stirring constantly, about 1 minute. Add chicken stock and wine; cook, stirring often, until sauce thickens slightly, about 6 minutes. Stir in cream and remaining 1⁄2 teaspoon salt and 1⁄4 teaspoon pepper; add chicken, bone side down, nestling chicken into sauce mixture.

Cover, reduce heat to medium-low, and cook until sauce has thickened slightly and chicken is almost cooked through, about 15 minutes. Uncover and sprinkle withasparagus. Cover and cook until chicken is cooked through and asparagus is tender-crisp, about 10 minutes.

Serve chicken, vegetables, and sauce over hot cooked noodles, and garnish with chives, if desired.