This is how I prepare frozen spinach. For one pound of spinach:
1- Chop one large onion
2- Cover the bottom of a pan with 1/8 of an inch of olive oil. Then, sautee the onion until compeletly translucent and soft and all the onion juice has evaporated. Do not let the onion brown.
3- Add spinach, still frozen and turn flame very low. Add 1/4 to 1/3 teaspoon freshly grated nutmeg, dash of black pepper, 2 chopped garlic cloves. Cover pan and let spinach simmer gently until very soft. Stir a few times in the process.
4- Add some salt (but not too much yet). Add 1 Tablespoon lime juice or 1/2 teaspoon pomegranate molasses. The lime juice or the molasses will give the spinach a tangy taste. Stir well. Taste. If needed, increase salt to decire taste. the salt will balance the tangy taste.
5- Eat it next day, after all the flavors have come together. Preserves well in the fridge for a week. Store in a glass container.