Preheat the oven to 375 degrees F.
In a large cast iron skillet over medium heat, sauté the onion in olive oil until soft and translucent, about 5 minutes. Add the minced garlic and sauté until fragrant, about 2 minutes more.
Add the diced tomatoes, El Greco,1/2 teaspoon Alderwood smoked salt and black pepper. Simmer over medium-low heat for 10-15 minutes until slightly thickened. Add the chopped spinach and stir until it is just wilted, then remove the pan from heat.
Sprinkle half the feta over the sauce and then make six little wells in the sauce with the back of a spoon. Crack one egg into each well and sprinkle the remining feta on top.
Put the pan in the oven and bake until the eggs are just set, 7-10 minutes. Remove the pan and garnish with parsley and Aleppo or Marash.
Serve immediately with pita or crusty bread.
Notes:
Adapted from New York Times by Melissa Clark.