Preheat the oven to 300F.
In a large (12”) cast-iron or oven-proof skillet over medium heat, warm the olive oil. Add the spinach and ½ teaspoon salt. Cook for 5-7 minutes, or until the spinach is softened and most of the water has cooked off, stirring occasionally. Stir in the parsley and then turn off the heat. Spread the greens out evenly in the pan.
Meanwhile, in a large bowl, add eggs, pepper, and remaining ½ teaspoon salt and whisk thoroughly until totally smooth (give it some muscle, you don’t want any egg white streaks in there - it should be uniform and a little bubbly when it’s done).
Pour the egg mixture into the pan, distributing it all around. Use a spoon to place small chunks of cream cheese evenly throughout.
Transfer to the oven and bake for 20-25 minutes, or until the eggs are mostly set and no longer jiggly in the center. Let the frittata rest for 10 minutes to finish cooking through and cool off.
Slice into about 8 slices and use a knife to loosen the edges. The first slice is always tricky to get out (best spatula for everything). Slice it up and serve topped with smoked salmon, herbs, a lemon wedge to squeeze over top, and a side of buttered toast.