Preheat oven to 425 degrees.
In a large bowl, combine the chicken, olive oil, oregano, parsley, garlic, lemon zest and lemon juice, generous pinch of salt and pepper, and potatoes. Stir to combine all the ingredients together.
Spread all the ingredients on a large rimmed baking sheet. Bake until chicken is fully cooked through, about 20-25 minutes. If you are using chicken breasts it will take about 10 minutes longer to cook them. For a broken-down chicken, depending on the size of the pieces, it will take about 45 minutes.
If the chicken is finished cooking before the potatoes (which will definitely be the case if you are using chicken thighs), remove the chicken with a slotted spoon and set aside.
Cover to keep warm.
When the potatoes are fork tender, add the mushrooms, and continue to cook for an addition 15-20 minutes. The potatoes will start to get brown and the mushrooms will be a lovely dark roasted color. Add the chicken back to the pan for the last couple of minutes, to warm it up.
Pour the chicken, potatoes and mushrooms into a large serving dish, drizzle with some olive oil and an extra squeeze of lemon juice, sprinkle with parsley. Serve immediately.