Peheat oven to 400 degrees
In an heavy bottom, oven safe skillet heat oil over medium heat until it shimmers
Season chicken thighs with salt and place skin down in skillet. Cook 5-8 minutes until golden brown. Remove from skillet and set aside
Add pearl onions to skillet with left over chicken fat and cook over medium heat until they start to brown, about 5-8 minutes. Add garlic and cook for another 1-2 minutes until fragrant.
Add 1 tablespoon flour and continuously stir until well combined, about 1-2 minutes. Add gin and chicken stock. Cook until it slightly thickens, about another 3-6 minutes.
Season to taste with salt and pepper. Add finely chopped parsley. Add chicken thighs back in, skin side up. Add in olives and transfer to preheated oven. Cook uncovered until chicken is cooked through and sauce thickens, 20-25 minutes.
When ready to serve, scoop couscous on a place, top with chicken and sauce. And serve with fresh lemon zest.