To spatchcock a chicken place it breast side down and with a sharp knife or kitchen scissors cut along one side of a backbone, then repeat with the other side. Remove the backbone and turn the bird the cut side down. Place the palm of your hand on the chicken breast and push down firmly to flatten it. Tuck the wing tips under the breasts to avoid burning.
Brush the chicken with olive oil, season with salt, pepper, garlic powder and thyme leaves. Cut the bigger baby potatoes in half, so they are all the same size, then toss in olive oil and salt and scatter around the chicken. Roast at 200/400 for 40 minutes until 165F/74C in the thickest part of the bird.
Mix melted butter with breadcrumbs and scatter over the chicken, broil until golden. It might take 2-3 minutes or longer depending on how close the chicken is to the element.