Make sure to carefully follow each step of the instructions for the best results :
Prep the oven and pan.
Preheat the oven to 400°F and line a large sheet pan with parchment paper or foil. A hot oven and a single, roomy pan help the chicken roast properly and allow the vegetables to caramelize instead of steam.Make the lemon garlic marinade.
In a bowl, whisk together the olive oil, lemon juice, lemon zest, garlic, thyme, rosemary, salt, pepper, and paprika. Rub most of the mixture over the chicken thighs, making sure they’re well coated. This kind of lemon-garlic-herb mixture is a common base for sheet pan chicken because it keeps the flavor fresh and bright while the chicken roasts.Season the vegetables.
Place the potatoes, carrots, bell pepper, and onion on the sheet pan. Drizzle with olive oil and season with salt and pepper, then toss well so everything is evenly coated. Spread the vegetables out in a single layer and nestle the chicken pieces in among them with a few lemon slices tucked around the pan.Roast until golden.
Bake for 35 to 40 minutes, or until the chicken is cooked through and the vegetables are tender and caramelized at the edges. The chicken should reach 165°F in the thickest part, though dark meat often tastes best when cooked a little longer until very tender.Finish and serve.
Let the pan rest for a few minutes, then scatter fresh parsley over the top and serve warm. Spoon any pan juices over the chicken and vegetables for even more lemon-garlic flavor.