Heat the oven to 220°C (430°F).
To a baking tray just large enough to hold the chicken legs, pour in the chicken stock, olive oil and juice of half a lemon, add the lemon slices and pounded garlic cloves, and give it a stir. Lay the chicken pieces down in the baking tray and spoon the liquid onto the chicken.
In a small bowl or empty salt shaker create your chicken seasoning by stirring the sea salt, garlic powder, onion powder, and white pepper to thoroughly combine, then shake or sprinkle a pinch of seasoning over the chicken pieces.
Slide the tray onto the middle shelf of the oven to bake for 50 minutes, setting a timer for every 15 minutes to baste the chicken with the liquid and sprinkle on another pinch of seasoning.
At 15 minutes, when you do the first basting, reduce the heat to 150°C (300°F). Continue basting every 15 minutes.
When the chicken is golden coloured (around 45 minutes), slide the tray out of the oven and poke a digital thermometer into the widest part of the pieces to check the internal temperature. Chicken is cooked at 74°C (165°F).
If the chicken is cooked, give it a final baste and sprinkle, then use a fish slice to transfer the pieces to a flat oven tray (one without sides so the chicken parts immersed in liquid get colour) and return the chicken to the oven for 5 minutes. If not golden enough, put the tray on the top shelf.
Pour the baking tray liquid into a saucepan and reduce over high heat to create a jus. When reduced, strain the jus, and return it to the sauce pan, add the butter, and stir.
Plate the chicken, pouring the jus over the pieces, and serve with sides of vegetables or salad and crusty bread to mop up the jus.