A note before you begin:
If you have time, spatchcock and season your chicken with salt and pepper the night before and leave it uncovered in the fridge overnight (there is no need to season again before roasting in this case). This not only seasons the chicken all the way to the bone but also dries out the skin, helping it crisp up beautifully in the oven. If you don’t have time, no worries—just follow the seasoning steps when you prep the chicken before cooking. 

1. Heat your oven to 190°C fan.

2. Make the herby butter by combining 80g butter, half the 15g chives, 2 cloves garlic, and 10g wild garlic (if using) in a food processor. Blitz until smooth, bright green, and well combined. Season generously with ground sea salt and pepper to taste.

3. Spatchcock your chicken (or ask your butcher to do this) by removing the backbone with kitchen scissors or a sharp knife. If you haven’t seasoned it yet, season all over with ground sea salt and pepper, inside and out.

4. Prep your potatoes: peel (if you like) and slice into 1mm-thick medallions using a knife or mandolin. Thinly slice the onion.

5. Butter the inside of a large shallow casserole dish or roasting tin with a little of the herby butter. Begin layering the potatoes: place two overlapping layers of potatoes to cover the base, scatter over some sliced onion and a generous pinch of the reserved chives, lightly season each layer with salt and pepper, then repeat—layering potatoes, onions, chives, and a light seasoning—until everything is used up. Finish with a final neat layer of potatoes.

6. In a jug, mix together 350ml of stock, 70g sour cream, and 1 grated garlic clove until smooth. Pour over the potatoes.

7. Cover the dish tightly with foil and bake for 15–20 minutes, until the stock is hot and the potatoes are beginning to soften.

8. While the potatoes bake, gently lift the skin of the chicken and press the herby butter underneath, distributing it around the thighs, legs, breast, and neck area.

9. Remove the potatoes from the oven, uncover, and place the spatchcock chicken, breast side up, directly on top of the potatoes.

10. Return to the oven and roast uncovered for 50–55 minutes, or until the chicken is golden and cooked through (the internal temp around the thickest part of the leg should reach 65°C).

11. Transfer the chicken to a board and let it rest for 15 minutes somewhere warm.

12. Increase the oven temperature to 200°C fan and return the potatoes to the oven for a further 10–15 minutes, until crisp and golden on top.

13. Carve the chicken, pour any resting juices back over the crispy potatoes, and serve.