Preheat the oven to 400F/200C.
Peel or scrub the carrots and cut into lengths around 2-3in/5-7cm long. Cut the potatoes into similar-sized pieces (I left skin on but peel if you prefer).
Toss the carrots and potatoes with the 2tbsp oil, ½tsp paprika and ½tsp salt in a large baking dish/casserole and roast in the oven for around 15-20 minutes.
Meanwhile, toss the chicken thighs with the lemon juice and zest, 1tbsp olive oil, ½tsp paprika - more if you'd like a little more of the taste -, ½tsp salt and sliced-up garlic cloves in a bowl.
Trim the ends off the beans and cut any long ones into slightly shorter lengths.
After the carrots and potatoes have had around 15-20min, add the beans on top followed by the chicken.
Roast for another approx 30 minutes until the chicken is cooked through (it may need a little more) and the vegetables are tender. Sprinkle over the parsley and serve - don't forget to spoon over the liquid at the bottom of the pan, it's delicious!
Note: The beans will still be a little crunchy but personally I like that. If you'd prefer them much softer, then pre-steam or boil them (or cook separately)