Preheat oven to 400°F.

Heat one-third cup of evoo in a skillet over medium heat. Add potatoes and onion and cook until potatoes are soft and tender with slightly crispy exterior (about 10 minutes). You may need to do this in batches, depending on pan size. Add garlic and continue cooking 2 minutes more until garlic is fragrant and slightly softened, but not browned. Transfer potatoes to a large mixing bowl.

Heat 2 tablespoons evoo in your omelet pan, or use the same pan and drain all but 2 tablespoons of evoo out of it, over low heat. Add whisked eggs, salt, pepper, spinach, and potato-onion mixture. 

Transfer the pan to preheated oven and bake at 400°F for about 5 to 7 minutes until eggs are barely set. Allow to cool for a few minutes in the pan before inverting on a serving platter.

Place a large platter over the skillet and invert the tortilla onto a plate. Serve warm or cold with salad and bread for the perfect light dinner, lunch, or brunch.