Baked mushroom & sweet potato rice

Ingredients

• 500 g sweet potato
• 2 tbsp olive oil
• 2 tsp chopped fresh rosemary
• 750 g swiss brown mushrooms, quartered
• 60 g butter, melted
• 1 tbsp olive oil, extra
• 4 garlic cloves, crushed
• pinch grated nutmeg
• 1 ½ cups long grain rice (uncooked)
• 1 ½ cups chicken stock
• 1 ½ cups boiling water
• ½ cup walnuts, chopped
• 2 tbsp chopped fresh chives