Preheat the broiler to high and adjust rack to 6-inches from element. Pat the scallops dry with a paper towel. Toss scallops and chorizo with 2 teaspoons olive oil in a medium bowl and season lightly with salt. Divide mixture evenly between two broiler-safe gratin dishes or one broiler-safe 8- by 8-inch square baking dish. Toss the remaining teaspoon of olive oil with the panko and parsley (if using) in a separate bowl, then top scallop mixture with crumbs. Cover each gratin dish tightly with foil. Place the dishes on a baking sheet and broil for 10 minutes. Remove foil, and broil an addition 3 to 4 minutes until the chorizo has blistered and the crumbs are lightly toasted. Top each dish with a handful of greens lightly tossed with olive oil and salt. Serve immediately.