Preheat the oven to 350°F.
Pat the chicken dry and season on both sides with salt and pepper.
Heat the olive oil in an oven-safe large, deep skillet over medium-high heat. Working in batches, add the chicken and cook until golden brown on each side, about 2 minutes per side. Transfer to a plate and set aside.
Add the onions, carrots, celery, and garlic and cook, stirring, for 1 minute.
Add the mustard, tomato paste, and paprika and stir until well combined.
In a small bowl, whisk together the chicken broth and arrowroot flour until well combined. Slowly pour in the broth mixture and whisk constantly until well combined.
Remove from the heat and stir in the apple cider vinegar, thyme, and bay leaves. Place the chicken on top of the veggies, skin side up. Cover, transfer to the oven, and bake for 40 minutes.
Remove from the oven and increase the heat to 400°F.
Remove the cover and carefully nestle the potatoes into the sauce, tucking them under the chicken (just be delicate moving around the chicken so the skin doesn’t fall off!). Transfer back to the oven and bake, uncovered, until the skin is a deep golden-brown and crisp, the potatoes are tender, and the sauce has thickened, about 30 minutes.
Remove from the oven and let cool for 10 minutes prior to serving. Garnish with parsley, if desired, and enjoy!