Spinach is cleaned, washed and cut into in large pieces. Add salt and stew with very little water. Once soft drain, chopped small pieces and fry in the butter. Then pour into a baking dish and sprinkle with sliced ​​julienne ham. Top to tap the eggs yolks and it is advisable to remain intact. Sprinkle with grated cheese and bake in a moderate oven for 20-25 minutes.