This 3-step meal puts chicken, wild rice and Brussels sprouts on the table in a little more than 30 minutes.
Preheat oven to 450 degrees, with racks in upper and lower thirds. Place chicken on a large rimmed baking sheet lined with aluminum foil. Add mustard, and toss to coat; season with salt and pepper.
On another large rimmed baking sheet, toss Brussels sprouts with oil; season with salt and pepper. Place chicken on upper rack and sprouts on lower rack; bake until chicken is cooked through and sprouts are browned around the edges, 25 to 30 minutes, turning chicken halfway through.
Meanwhile, cook rice according to package instructions. Add thyme, season with salt and pepper, and fluff with a fork. Serve chicken with rice and Brussels sprouts.