Preheat your oven to 200 C. Oil 4 ramekins or Pyrex 10 ounce dishes.
Heat the oil in a medium saucepan, add the onion and saute until soft, about 5 minutes. Add the spinach and saute until wilted, about 2 minutes, then remove the pot from the heat. If you are going to be using Pyrex dishes, let this cool to room temperature.
In a mixing bowl, mix together the tomatoes, cumin, salt, pepper, paprika, and hot sauce if using. Then stir in the spinach mixture until just combined. Divide into the 4 ramekins or Pyrex dishes and make a depression in the center of each.
Crack an egg into each dish and sprinkle with the Feta cheese. Bake for 12 to 15 minutes, until the whites are set and the yolks still soft.
Serve with some toast for a breakfast, lunch, or even a light dinner.