Preheat the oven to 425°F (220°C)
In a large bowl, combine Parmesan, panko breadcrumbs, thyme, rosemary, salt, and pepper. Mix well.
Brush the chicken with Dijon mustard using a pastry brush, then coat each piece thoroughly in the Parmesan mixture.
Arrange the potatoes, carrots (and optional parsnips), and lemon wedges in the base of a large oven dish.
Pour the chicken broth over the vegetables, then place the coated chicken on top.
Bake in the preheated oven for about 30 minutes, until the chicken is cooked through and the vegetables are tender. The chicken should reach an internal temperature of 165°F (74°C) when done.