Preheat the Oven: Preheat your oven to 400°F (200°C).
Prepare the Glaze: In a small bowl, mix together the maple syrup, Dijon mustard, olive oil, garlic powder, salt, and pepper.
Arrange the Chicken: Place the chicken thighs on a sheet pan. Brush half of the maple Dijon glaze over the chicken, reserving the rest for later.
Add the Vegetables: In a bowl, toss the sliced carrots and halved Brussels sprouts with olive oil, thyme, salt, and pepper. Spread them around the chicken on the sheet pan.
Roast: Bake in the preheated oven for 30-35 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F (75°C). In the last 10 minutes of cooking, brush the remaining glaze over the chicken.
Serve: Garnish with fresh parsley if desired, and enjoy your flavorful sheet pan meal!