Heat oven to 400°F. Heat oil in large oven-safe skillet on medium. Add onion and sauté until golden brown and tender, 8 minutes. Stir in garlic, cumin and ½ teaspoon each salt and pepper and cook 1 minute. Stir in tomatoes, transfer to oven and roast 10 minutes.  Remove pan from oven, stir, then make 8 small wells in vegetable mixture and carefully crack 1 egg into each. Bake eggs to desired doneness, 7 to 8 minutes for slightly runny yolks. Sprinkle with spinach and, if desired, serve with toast.