Mince the half red onion and chop the garlic clove finely. Roughly chop the fresh parsley in advance and set it aside for later garnishing.
Heat the olive oil in a frying pan over medium-high heat. Sauté the onion and garlic until they look translucent. Then add the baby spinach and cook until the leaves are completely wilted.
Pour the sieved tomatoes over the spinach in the pan. Stir in the ground cumin, smoked paprika powder and cayenne pepper thoroughly. Lower the heat slightly and let the sauce simmer gently for five minutes.
Make two indentations in the warm tomato sauce with a spoon and gently crack the eggs into them. Crumble the sheep's feta over the sauce around the eggs. Cover the pan and let the eggs cook for six to eight minutes until the whites are set but the yolks are still soft.
Remove the pan from the heat. Sprinkle the fresh parsley over the dish and serve the shakshuka directly from the pan.