Heat the oven to 220C/200C fan/gas 7. Put the chicken in a large roasting tin.
Mash together the garlic and butter. Gently separate the skin from the chicken breast by easing your fingers between the two and then push as much butter mixture under the skin as possible.
Rub whatever is left into the outside of the chicken and between the thighs and the breast then cook the chicken for 20 mins.
Turn the oven down to 190C/170C fan/gas 5 and cook for a further 45 mins or until the chicken juices run clear when you pierce the thigh with a knife. Leave to rest for 15 mins before carving.
Serve with seasonal veg and if you want a further garlic hit stir some of the wild garlic butter into mashed potato.