Preheat the oven to 200℃.
Then, season the chicken from the inside. In a bowl, add melted butter, tarragon, salt, and pepper and mix.
Rub this butter over and under the skin of the chicken.
In a bowl, add chickpeas, chilies, lemon zest, salt, pepper, and some olive oil and mix well. Add this stuffing to the chicken cavity and place a whole lemon in it.
In a roasting pan, add the garlic heads and place the chicken over them. Drizzle olive oil over the chicken and sprinkle salt and pepper over them. Place the pan in the oven and roast for 10-15 minutes until it just starts to crisp.
Then, decrease the temperature of the oven to 180℃ and roast the chicken for about 1½ hours until it is perfectly cooked and golden.
Take out the lemon from the cavity and then take out the stuffing and put it on a plate. Cover the chicken in foil and let it rest for 10-15 minutes.
For the salad, add the teared-up lettuce leaves, avocado, and spinach. Mix vinegar, olive oil, honey, and mustard in a bowl and drizzle about 2 tablespoons of the dressing over the salad.
Add the garlic from the roasting pan to the stuffing bowl and squeeze half a lemon over it as well. Mix it and then mash it. Add a tablespoon of oil to this and mix.
Serve the baked chicken with mashed stuffing and the salad.