Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper for easier cleanup, if desired.
In a large bowl, combine the olive oil and fresh lemon juice. Add the dried oregano, thyme, garlic powder, onion powder, salt, and pepper. Whisk together to create the marinade.
Add the chicken pieces to the bowl and toss to coat evenly. Let it marinate for at least 10 minutes while you prepare the broccoli.
Add the broccoli florets to the same bowl (no need to wash it). Toss the broccoli in the remaining marinade until well coated.
Arrange the marinated chicken pieces in a single layer on one side of the prepared baking sheet. Place the coated broccoli florets on the other side of the baking sheet. If using, tuck the lemon slices amongst the chicken and broccoli.
Roast for 20-25 minutes, or until the chicken is cooked through (internal temperature reaches 165°F or 74°C) and the broccoli is tender-crisp and slightly charred at the edges. Cooking time may vary slightly depending on the size of your chicken pieces and broccoli florets.
Remove from the oven. Garnish with fresh chopped parsley before serving.