Chop the garlic finely. Sprinkle the salt over the garlic and continue to chop it, occasionally smashing and smearing the garlic with the flat side of your blade, until the garlic becomes pastelike. (Alternatively, smash the garlic and salt together in a mortar and pestle.) Place the garlic paste in a small bowl and add the butter, cayenne, lemon juice, rosemary, thyme, and the 2½ tablespoons parsley. Mash together with a fork. Refrigerate and reserve.

Shuck the clams (see Note) and place each clam on the deeper half shell. Press about 1 teaspoon of the flavored butter onto the clam. Refrigerate until ready to cook.

Heat the broiler. Place the clams on a sided baking sheet and broil until the butter is melted and sizzling and the clam is cooked through, 3 to 5 minutes. (The cooking time will vary depending on the kind of broiler you use.) Sprinkle with the remaining chopped parsley and serve immediately with lemon wedges and crusty bread to soak up the extra butter.