Moroccan chicken with sweet potato mash

INGREDIENTS

• 1kg sweet potatoes , cubed
• 2 tsp ras-el-hanout , or a mix of ground cinnamon and cumin
• 4 skinless, boneless chicken breasts
• 2 tbsp olive oil
• 1 onion , thinly sliced
• 1 fat garlic clove , crushed
• 200ml chicken stock
• 2 tsp clear honey
• juice ½ lemon
• handful green olives , pitted or whole
• 20g pack coriander , leaves chopped