Toss potatoes, carrots, and onions with EVOO, salt and pepper. Put in the oven for 10 minutes.
Sprinkle chicken with salt and pepper
Combine 2 tablespoons EVOO, mustard, shallot, thyme in bowl. Add chicken and toss to coat.
Remove veggies from oven and place chicken on top of veggies.
Turn oven down to 375 and put chicken in oven
Bake about 45-50 minutes
Notes
The veggies will take a little longer than the chicken. That is why they get a headstart.
I have listed potatoes, onions and carrots for the veggies, but you can use whatever combinations of veggies you like.
You can also roast the veggies in a separate pan. The veggies will get a little browned (a good thing) because they are less protected by the chicken. It also makes it easier to pull the chicken and veggies out of the oven when each is done.