Clean/Scrub mussels with a brush and remove beards.
Fill a large saucepan with water and place mussels in. Cover.
Over medium heat bring to the boil. Reduce heat to medium-low. Simmer for about 5 minutes or until mussels open.
Drain and discard any mussels that have not opened. Break top shells off remaining mussels and discard.
Place mussels on shells onto a baking tray.
Preheat grill on medium heat.
Place breadcrumbs, parsley, cheese, butter, lemon rind, and salt and pepper into a bowl.
Combine well. Spoon mixture onto mussels.
Grill for 1 - 2 minutes or until topping is crisp and golden.
Serve warm.