Skip the steaming fresh spinach step if desired and use frozen spinach instead. Add about 1 tablespoon to each muffin cup.
These smoothie pucks work best if you use a smaller container to freeze them, such as muffin cups. Thicker pucks will be harder to blend. If your blender has a tamper, you may need to use that to facilitate blending. Otherwise, you may need to stop the blender periodically to scrape the contents down until fully blended. Add more water as needed to get the desired consistency.