In a medium mixing bowl, whisk together ¼ cup of olive oil, ½ cup of water, 1 teaspoon of garlic powder, 2 teaspoons of dried oregano, 1 teaspoon of dried thyme, and salt and pepper to taste. Zest and juice half of a lemon, adding both to the marinade for a bright flavor. Set aside the lemon slices for later use.

Slice one red onion into wedges, then cut the chicken breasts into equal-sized pieces to ensure uniform cooking. Clean and cut approximately 1.5 pounds of Yukon potatoes into wedges about 1 inch thick.

In a large resealable plastic bag or a shallow dish, add the chicken pieces, onion wedges, and potato wedges. Pour the marinade over the ingredients, ensuring everything is evenly coated. Seal the bag or cover the dish, allowing it to marinate for at least 20 minutes, or up to 2 hours in the refrigerator.

Preheat your oven to 425°F (220°C). Generously coat a large rimmed baking sheet with olive oil to prevent sticking.

Once marinated, transfer the chicken, potatoes, and onions to the prepared baking sheet in a single layer. Place the reserved lemon slices on top of the chicken. Roast for about 30 minutes, checking for doneness.

At the 30-minute mark, use a meat thermometer to check that the thickest part of the chicken has reached 165°F (74°C) and that the potatoes are fork-tender. Let them roast for an additional 5 to 10 minutes if necessary.

Once baked, remove from the oven. Garnish with chopped parsley and Parmesan cheese if desired. Serve warm.