Fresh loose-leaf bundles are the healthiest, but you can also prepare this easy side dish with frozen or packaged spinach. Just heat 2 tbsp. olive oil and sautée spinach over high heat for two to three minutes. For extra flavor, add your favorite seasonings, like one clove of garlic (minced) or 1/4 teaspoon crushed red pepper. Tip: Cook up two bundles of spinach, since the leaves shrink.