How to Make It
In a small skillet, toast the panko over moderate heat, stirring, until lightly golden, 2 minutes; transfer to a bowl. Stir in 1 tablespoon of the olive oil and season with salt.
In another bowl, combine the parsley with the cheese and half of the garlic. Stir in the 1/2 cup of oil and season the pesto with salt.
In a large, deep skillet or pot, stir the mussels over high heat for 2 minutes. Add the remaining garlic and 2 tablespoons of olive oil and cook for 1 minute. Add the white wine, cover with a tight-fitting lid and cook just until the mussels open, 3 minutes. Drain the mussels and let cool on a baking sheet. Loosen the mussels in their shells and discard the empty half shells.
Preheat the broiler and position a rack about 8 inches from the heat. Spoon the parsley pesto over the mussels and sprinkle with the panko. Broil until the crumbs are golden, about 6 minutes, shifting the pan for even browning, then serve.