Heat the oven to 425 F.
Combine all the chopped vegetables in a large bowl.
In a small bowl, whisk together olive oil, maple syrup, Dijon mustard, rosemary, salt and pepper.
Brush the chicken thighs with the marinade, then pour remaining marinade over the vegetables. Stir well to combine the marinade with the vegetables, and add another tablespoon or two of olive oil if needed.
Arrange the vegetables and chicken on a baking sheet.
Bake for 35-40 minutes, until the chicken has cooked through to 165 F and the vegetables are roasted. Serve and enjoy!