Moroccan chicken with pistachio and coriander couscous

Ingredients

• 1 1/2 teaspoon ground cumin
• 1 1/2 teaspoon ground cinnamon
• 2 teaspoons smoky paprika
• 2 teaspoons garlic salt
• 1/4 cup olive oil
• 8 chicken thighs on the bone
• 1/2 cup natural yoghurt
• 1 tablespoon lemon juice
• 1 1/2 tablespoon chopped fresh chives
• sea salt
• 2 cups chicken stock
• 2 cups couscous
• 1 tablespoon butter
• 1/3 cup shelled pistachio kernels, chopped coarsely
• handful fresh coriander leaves, chopped coarsely
• freshly ground black pepper, to taste