3 10-oz. packages frozen chopped spinach
5 tbsp butter
salt, pepper
1 1/2 tbsp flour
1 cup beef stock or cream
1/2 cup grated Swiss cheese
Unwrap spinach and thaw slightly. Cut it into small blocks. Melt 1 1/2 tablespoons butter in a stainless steel skillet or pan. Stir in chopped spinach and 1/4 teaspoon salt. Cook slowly until thawed and juices are released. Uncover, raise heat, and stir for a minute or two until all moisture has evaporated. Stir in the additional butter, plus salt and pepper to taste. Cover and cook very slowly for 10 to 15 minutes, stirring frequently, until the spinach has absorbed the butter and is very tender.
Sprinkle flour on the spinach; cook for two minutes. Add 2/3 of the liquid by spoonfuls. Simmer, cover, and cook slowly for about 15 minutes, stirring frequently. Add more liquid if needed. Stir in grated cheese.
* If not needed immediately, set aside uncovered and film the top with a tablespoon of stock or cream. Reheat when needed.