
Bring a large pot of salted water about 2cm (1in) deep to a rolling boil.
Trim and discard the spinach stems. Pile the leaves on top of one another to make a tall stack, then roll tightly into a cylinder. Slice leaves into 2cm thick (1in) ribbons.
Drain in a colander and rinse with cold water to cool and stop the cooking process. Squeeze as much water out as possible. Roll into golf ball shapes and place on a plate (or pack into ice cube trays).
Pop plate / tray in the freezer for 8 hours or overnight.
Once the spinach is frozen transfer to a ziplock bag. Keeps in the freezer for months.