Although I do prefer my spinach fresh, I always have a bag of frozen spinach in the freezer to use whenever I need it. (savormania.com)
Using frozen spinach instead of fresh speeds the cooking time and allows you to use a smaller pot — but feel free to substitute 2 cups steamed fresh spinach. (vegetariantimes.com)
Also, use frozen spinach in lieu of fresh, because it's equally yummy and a huge time - saver. (marthastewart.com)