Tuna Macaroni and Cheese Bake

Ingredients

• 1 cup (150 g) elbow macaroni
• 2½ tablespoons (50 g) butter
• 1 onion, finely chopped
• 2 tablespoons plain flour
• 2 cups (500 ml) milk
• 1 tablespoon wholegrain mustard
• ½ cup (60 g) grated cheddar
• 185 g can tuna in springwater, drained
• 2 tablespoons chopped fresh flat-leaf parsley
• salt and freshly ground black pepper
• 1 cup (80 g) fresh breadcrumbs