8 fat garlic cloves, bruised and slightly splintered with the flat side of a wide-bladed knife, then slipped out of their skins
2kg/4lb 8oz potatoes, such as Maris Piper, peeled and cut into large equal-sized chunks
50²µ/1¾´Ç³ú dried breadcrumbs or panko
2 tsp sea salt flakes, plus extra to taste
75g/2½oz unsalted butter, softened
50²µ/1¾´Ç³ú unsalted butter, in blobs or teaspoons
50²µ/1¾´Ç³ú Parmesan, finely grated
35²µ/1¼´Ç³ú Parmesan, finely grated