Bring a 2 quart pot filled ¾ with water to boil. Add the potatoes and cook for 5-6 minutes until tender, but not completely cooked through. Drain and set aside.
Heat a medium sized skillet over medium heat and add 1 tablespoon of coconut oil. Wilt the spinach for 1-2 minutes. Turn the spinach out into a large mixing bowl. Add the whisked eggs and most of the parmesan cheese (reserve a couple of tablespoons to sprinkle on the top) and season well with chives, salt and freshly ground black pepper.
Grease a pie pan with 1 tablespoon of coconut oil. Arrange the potatoes out in a circle, laying up (but not layering above the rim of the pie pan). Pour the egg mixture slowly over the potatoes.
Arrange the tomato slices over the top of the frittata and then sprinkle the remaining parmesan cheese.
Bake for 20-25 minutes, until the center is slightly puffed up.
Notes
To make this dairy free, omit the cheese. You may also replace the potato with sweet potato.