Preheat the oven to 375 F/ 190 C. In an 8- or 10-inch (20-25 cm), ovenproof, preferably cast-iron, skillet. Heat the olive oil over medium flame and brown the chorizo lightly. Add the tomatoes and garlic. Cook until most of the juices are simmered off, about 8 minutes. Add the parsley and season lightly with salt and pepper.

In the meantime, whisk the eggs and whites with a little salt and pepper. Pour over the contents of the skillet, tilting it so that the eggs are distributed evenly. Once the eggs begin to set slightly, sprinkle the cheese on top and transfer to the oven. Bake for about 15 minutes, or until set, moist but not runny. Remove, cool slightly, and serve.