Preheat oven to 400 degrees. Line a rimmed baking sheet with foil.
Trim the chicken. Halve the potatoes and mushrooms (cut any especially large ones in thirds), and place the chicken, potatoes, and mushrooms in a large bowl.
Combine the olive oil, garlic, and seasonings in a small bowl.
Pour the olive oil mixture over the chicken and potatoes, and toss until everything is well coated.
Arrange the chicken, potatoes, and mushrooms in a single layer on the prepared baking sheet.
Roast at 400 degrees for 40 minutes or until chicken is cooked to 160 degrees, stirring potatoes halfway through.
Broil for 2 minutes to crisp up the skin a bit more.
Notes
Combining the chicken and veggies with the olive oil mixture is easiest if you use your hands, just be prepared to wash them well afterwards!