Preheat the oven to 170°C / 340°F.
Add the chicken to a large mixing bowl.
Season with salt, pepper, garlic powder, dried thyme, and oregano.
Cut the lemon in half and squeeze it into the bowl with the chicken. Don't discard the squeezed lemon halves.
Drizzle chicken with ½ cup of olive oil.
Marinate at room temperature for 30 minutes. Or in the fridge for up to 24 hours. Let it come to room temperature for 30 minutes before cooking. Place the chicken and all the juices/oil from the bowl in a baking pan or baking dish. I used one that's 27 x 35 cm (10 x 14 inches).
Chop the garlic into chunks and toss it in the pan.
Cut the squeezed lemon halves in half and toss them in the pan as well. Pour also 60 ml (¼ cup) of water.
Cover with parchment paper and aluminum foil on top.
Bake for about an hour.
Add the orzo all around the chicken. Make sure it doesn't sit on top of the chicken, or it won't cook.
Pour the hot water or stock, making sure the orzo is submerged. Tilt and shake the pan a little to help it sink.
Bake uncovered for 30 minutes. Orzo should be cooked, but the food should still look slightly soupy. Because as the orzo sits and cools, it's going to absorb it and thicken.
Let the food rest in the oven for 20 minutes with the oven door open.
Serve with plenty of freshly ground pepper and grated cheese on top.