Bring a large pot of salted water to a boil. Add the pasta and cook as the label directs. Reserve 1/2 cup cooking water, then drain.
Meanwhile, heat the olive oil in a large skillet over medium heat. Add the garlic, red pepper flakes and 1/2 teaspoon salt; cook until the garlic is lightly golden, about 2 minutes. Add the clams, scallops and lemon zest. Cook, stirring, until the scallops are just cooked through, about 2 minutes.
Add the pasta, reserved clam juice, lemon juice, parsley and parmesan to the skillet; cook, tossing to coat, 1 minute, adding the reserved cooking water as needed to loosen. Season with salt and pepper. Drizzle each serving with olive oil and top with more parmesan.
Photograph by Ryan Dausch
Courtesy of Food Network Magazine