Season with salt and pepper to taste, add the finely chopped garlic and mix all the ingredients thoroughly. Cover the mussels with a teaspoon of bread topping and, finally, add a drizzle of oil. Pop the mussels into an oven preheated to 180°C for 5 minutes. When the bread topping is golden brown and crisp, your gratin mussels are ready. Serve while still nice and hot.
Useful tips and interesting facts
When cleaning the mussels, make sure to discard any open or broken shells. In this case, the mollusc will no longer be alive and it is therefore advisable not to eat it.
If you want the mussels au gratin to be even crisper, oven bake them for three minutes before passing them under the grill for the final two minutes.
Mussels au gratin is typically eaten in Southern Italy, especially in Puglia. Serve them as a starter to a fish dinner or as finger food together with an aperitif.
For a different version of mussels au gratin, you may enrich the bread topping with a spoonful of grated Parmigiano Reggiano which will make the dish even taster. Instead, for a more summery and fresh flavour, add a cherry tomato concassé.