In a large 12-inch oven-safe skillet, layer the lemon slices, onions, garlic, and potatoes. Drizzle lightly with olive oil and season with salt and pepper. Place the chicken, skin side down, over the potatoes and brush with half of the herb oil. Flip the chicken skin side up and coat in the remaining oil, being sure to cover the chicken completely.
You can ask the butcher remove the backbone and butterfly the chicken or do it yourself. To do it yourself: start by removing any chicken giblets, if applicable. Pat the outside dry with paper towel. Place the chicken on a cutting board, breast side down, so that the chicken's back is facing up. Using a pair of sharp kitchen scissors, cut closely along either side of the backbone. Remove the bone and discard. Turn the chicken over so the breast is now facing up and press down firmly with the open palm of your hand on the breast and flatten the chicken.
Recipe adapted from: Gerard, Tieghan. "Spring Skillet Roasted Lemon Chicken and Veggies." Half Baked Harvest. April 2018.