Butter Chicken Mac ‘n’ Cheese

• 1 tablespoon butter
• 2 ¼ cups chicken (300 g), chopped
• salt, to taste
• pepper, to taste

Sauce

• 1 onion, chopped
• 1 tablespoon plain flour
• 1 ¼ cups milk (300 mL)
• ¼ cup butter chicken sauce (50 g)
• 2 ¼ cups mozzarella cheese (250 g)
• 2 ½ cups cheddar cheese (250 g)
• 1 cup elbow pasta (200 g), cooked
• 1 cup mozzarella cheese (100 g), grafted
• fresh coriander, to garnish