1. Preheat oven to 350 degrees Fahrenheit (180 degrees Celsius). Place chicken on baking sheet or roasting dish and pat dry.
2. In a food processor combine parsley, lemon zest, garlic, salt, and pepper. Blend until everything is finely minced and incorporated.
3. Whilst food processor is running slowly drizzle in olive oil, juice of lemons, and mustard. Divide the marinade in half.
4. If using whole chicken add half marinade to inside the cavity. If using spatchcock add half marinade to underside of the chicken.
5. Use your finger to loosen the skin from the flesh and apply half the remaining marinade underneath the skin to directly touch the flesh of the chicken. Apply remaining marinade all over the outside of the chicken, making sure to get to all the nooks and crannies.
6. If using a whole chicken, stuff used lemon halves inside the cavity. If using spatchcock chicken, spread them around the chicken. Place the vegetables around the chicken and season with salt, pepper, and olive oil.
7. Place chicken uncovered in oven and bake for approximately one and a half hours until chicken is golden brown and crispy.