Preheat oven on the broiler setting.
Chop the Scallion (4), separating the whites and greens.
Crumble the Feta Cheese (2 ounce). Roughly chop the Fresh Spinach (3 ounce), removing any stiff stems.
In a medium bowl, beat the Egg (6), with a whisk for 3-4 minutes. Add the Ground Black Pepper (1 teaspoon) and Sea Salt (to taste) to the eggs and whisk for another minute.
Heat a 10-inch oven-safe frying pan over medium heat. Add Butter (1 tablespoon) and tilt the pan until butter coats the bottom. Cook spinach for 2-3 minutes until it has wilted and collapsed in size. Add scallions and cook for 2-3 more minutes.
Pour in egg mixture and quickly stir so the spinach and scallions are evenly distributed. From this point on, do not stir the mixture. Sprinkle the Feta Cheese evenly over the top of the eggs.
Once the edges of the frittata are cooked (they’ll be lighter in color and look solid), place the frying pan on a middle rack in the oven. Broil for 6 minutes, watching very closely so that it doesn't burn.
Once the frittata is starting to turn golden-brown and is puffing up, remove from the oven and allow to cool for 2-3 minutes.
Cut the frittata into six wedges and serve immediately.