Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.
Place the sweet potato, red potato, red onion, Brussels sprouts, green beans, and carrots on the baking sheet in separate piles.
Drizzle everything with olive oil, then sprinkle with salt, pepper, thyme, and rosemary. Rub the seasoning into the vegetables until evenly coated and spread flat on the baking sheet, keeping the vegetables separate. Set aside.
In a small bowl, combine the mustard, honey, garlic, salt, and pepper, and whisk until smooth. Set aside.
Place the chicken thighs skin-side down in a greased cast-iron skillet. Season with salt and pepper, then brush generously with the honey-mustard sauce. Flip the chicken thighs over and repeat, seasoning with salt and pepper, then brushing with the rest of the honey-mustard sauce.
Place the vegetables and the chicken in the oven on separate racks. Bake for 30 minutes or until chicken reaches an internal temperature of 165°F (75°C) . (Optional: Remove the vegetables once cooked and broil the chicken for 1-2 minutes, or until the skin crisps up.)
Let everything cool, then distribute into resealable containers, mixing up the combination of vegetables so that you get something a little different each day.