Mix the cheddar and mozzarella together
Lay out the bread and spread with mustard
Sprinkle one of the slices with the cheddar and mozzarella mix
Place the remaining slice on top and press down gently
Put the sandwich into an oiled toaster and cook for 8 minutes
At the 8 minute mark open the toaster and sprinkle the Parmesan on top then close the lid
Cook for 2 minutes and then remove, including any cheese stuck on the sandwich maker. You really want to get all these crispy bits for a change of texture and flavor.