Preheat oven to 375 degrees. Combine the spinach and cream cheese and blend well until smooth. Add nutmeg and salt and pepper to taste. Distribute mixture into 4 individual gratin dishes. Make a slight indentation in the center of each dish and carefully break 1 egg into each dish. Cover with grated cheeses and bake uncovered until the eggs are set and cheese is melted and crusty. Cook about 20 minutes. If using a convection oven reduce heat to 350 and extend cooking time by 10 minutes. Garnish with sliced tomatoes. Serves 4.