Preheat your oven to 200°C (fan-forced).
Dry the chicken using a paper towel. This step is crucial to help the compound butter stick to the chicken.
In a bowl, combine the softened butter, smoked paprika, salt, pepper, finely chopped rosemary, minced garlic, and lemon zest. Mix everything well until it forms a thick paste.
Using a large spoon, carefully lift the skin of the chicken breast and place a good amount of butter on each side. Then, place the chicken on its back and gently push the butter around so it is evenly layered.
Stuff the chicken with the quartered onion, fresh thyme, fresh oregano, and lemon carcasses.
Use cooking string to tie up the legs and tuck the wings under the chicken.
Butter the back and sides of the chicken. Flip the chicken and butter the breast side.
Add a little more salt and pepper to your liking, and finish by drizzling with olive oil.
Place the chicken onto a wire rack inside a baking tray.
Place the tray into the oven and cook for 10 minutes.
Turn the oven down to 175°C (fan-forced) and continue to cook for another 50 minutes. (Start to prepare your rice.)