Preheat the oven to 425 degrees F. Line a large sheet pan with parchment paper or foil for easy cleanup.
Place the chicken breasts in the center of the pan. Arrange the halved potatoes, broccoli florets, and sliced bell pepper around the chicken.
In a small bowl, stir together the minced garlic, juice from one lemon, olive oil, oregano, salt, and black pepper. Drizzle this mixture over the chicken and vegetables. Toss the vegetables lightly to coat.
Slice the second lemon and tuck the slices among the chicken and vegetables on the pan.
Bake for 25 to 30 minutes until the chicken reaches 165 degrees F and the potatoes are tender when pierced with a fork.
Remove the pan from the oven and sprinkle the chopped parsley over everything before serving.