Scrub the mussels under cold running water and remove any beards. Tap open mussels firmly on the counter and discard any that don't close.

Place a large pot over high heat. Add the smashed garlic clove and 60 ml of white wine. When the wine starts to steam, add the mussels and cover with a tight lid.

Cook for 2 to 3 minutes, shaking the pot once, until the mussels just open. Remove from heat immediately - do not overcook. Discard any mussels that remain shut.

Lift each mussel from the pot and discard the empty top shell, leaving the mussel sitting in the bottom half-shell. Set aside on a tray to cool slightly.

Heat the oven to 220 C / 425 F with the grill element on if your oven has a combined setting, or plan to switch to grill for the final 2 minutes.

In a bowl, combine the breadcrumbs, grated garlic, chopped parsley, lemon zest, white wine, and olive oil. Add Pecorino Romano if using. Mix with a fork until the crumbs are evenly coated and just hold together when pressed. Season with a pinch of salt and black pepper.

Spread the coarse sea salt in an even layer across a rimmed sheet pan. Nestle the half-shell mussels into the salt so they sit level and don't tip.

Press a heaped teaspoon of the breadcrumb mixture firmly onto each mussel, covering it in an even layer. Drizzle a few drops of olive oil over the top of each.

Bake on the top rack of the oven for 8 to 10 minutes, until the topping is golden at the edges. Switch to grill / broil for the final 2 minutes to blister the crust to an even amber color.

Remove from the oven and serve immediately on the tray or transfer to a flat board. Put lemon wedges alongside.