How to Make It
Heat a large skillet over medium. Add oil to pan; swirl to coat. Add onion, and cook, stirring occasionally, until translucent, about 4 minutes. Add cumin, coriander, paprika, cinnamon, and garlic; cook, stirring occasionally, until garlic is soft and spices are fragrant, about 1 minute. Transfer to a 5- to 6-quart slow cooker.
Stir in crushed tomatoes, harissa, and 1/2 teaspoon salt. Cover and cook on HIGH 20 minutes; reduce heat to LOW, and cook until sauce is fragrant, 7 1/2 to 8 hours (or cook on HIGH for 3 to 4 hours).
One at a time, crack eggs into a ramekin, and slip into tomato sauce. (Do not stir.) Cover and cook on HIGH until whites are set and yolks are runny, about 15 to 20 minutes. Sprinkle eggs with remaining 1/4 teaspoon salt. Divide spinach evenly among 4 plates; top with sauce and eggs. Sprinkle with cilantro.