Take the chicken out of the fridge approximately 30 minutes before you begin to allow it to come up to room temperature.
1 large, whole chicken
Make a note of the weight of the chicken. You will need this to calculate the cooking time.
To make the compound butter for the stuffing, add the softened butter, garlic paste (or chopped garlic), dried oregano, chopped thyme, coarse sea salt and black pepper to a bowl.
110 grams ( 1 x US stick) unsalted butter, softened, 4 teaspoons garlic paste, 1 tablespoon dried oregano, 1 teaspoon coarse sea salt, ½ teaspoon freshly ground black pepper, 1 teaspoon fresh thyme, chopped
Using a fork, squash and mix all the ingredients together until thoroughly combined. Set aside.
In a large roasting dish, arrange the quartered onions and halved garlic heads to create a 'bed' for the chicken. See note 1 1 large onion, quartered, 1 whole garlic head, halved horizontally
Preheat the oven to 220C/430F.
Remove the chicken from its packaging and place it on a layer of kitchen paper. Gently pat the entire bird bone dry with another piece of paper towel.This step is crucial to ensure a crispy skin. To make it easier to put the butter under the skin, loosen the skin from the bird first. Use a big spoon or spatula to gently slide between the flesh and the skin, separating it as you work your way around the top half of its body. Just be careful not to tear the skin in the process. Do the same for the legs. You should be able to find an entry point near the loose skin around the cavity entrance of the chicken.See note 2 Set aside approximately a quarter of the compound butter. This reserved portion will be used for the outside of the chicken.
From the remaining butter, pinch off about two teaspoons worth of compound butter with your fingers.
Gently push the dollop of butter underneath the skin, moving it up towards the top of the chicken breasts. Follow with more dollops of butter until you've placed a few across the largest surface area of the chicken.
Press down on the outside surface of the skin to gently massage the butter underneath, flattening and spreading it out slightly.
Follow the same process for the chicken legs, pushing the butter in and then gently massaging it from the outside to spread it out more.
Briefly microwave the butter you set aside earlier until it becomes a bit runnier. Evenly pour it over the outside of the chicken.
Use your hands to spread the butter around the chicken's body, thighs and legs (Ignore the underside of the chicken).
Slice the lemon in half and stuff one half inside the chicken's cavity.
1 lemon, halved
Follow the lemon with a few sprigs of thyme or rosemary, pushing them up into the cavity.
small handful of thyme or rosemary sprigs
Optional: Truss the chicken's legs together with a piece of butcher's string. See note 3 Take a generous pinch of coarse sea salt and sprinkle it across the chicken. We've found that a three-finger-and-thumb pinch is just the right amount.
large pinch of coarse sea salt
Transfer the chicken onto its onion and garlic trivet. Feel free to add more fresh herbs below the chicken if you wish.
With the remaining half of the lemon, squeeze a small amount of juice across the chicken, followed by freshly ground black pepper.See note 4 freshly ground black pepper
Cook the chicken for 10 minutes at 220C/430F then turn the heat down to 180C/356F. Then, cook it for 20 minutes per every pound (450g) of chicken. Check that the juices from the chicken are running clear before removing it from the oven. See note 5 Allow the chicken to rest for 15 minutes before slicing. Do not cover the chicken at this point because any steam trapped inside foil will soften the crispy skin.