Position a rack in the upper third of the oven and heat the broiler.
Thread the shrimp, fish and scallops onto four metal skewers, alternating them. Drizzle with EVOO to coat and sprinkle with a little sea salt and pepper. Broil, turning occasionally, until firm and opaque, 7-8 minutes.
Meanwhile, heat 3 tablespoons EVOO in a large saucepot over medium heat. Add the garlic and chili pepper and cook, stirring, for 2 minutes. Add the spinach, a few handfuls at a time, and cook until wilted. Season with salt, pepper and a little nutmeg.
Arrange the spinach on a serving platter. Top with the seafood skewers and douse the spinach and seafood with the lemon juice.