Soak the gelatin in cold water.
Thaw the spinach, then bring to a boil in a saucepan with 200 ml (approximately 1 cup) of water. Season with salt, pepper and Worcestershire sauce and puree in blender.
Squeeze out the gelatin, stir 5 tablespoons of the hot spinach mixture into the gelatin to melt, then stir the gelatin into the remaining spinach. Pour into a small bowl and let cool, then refrigerate for about 4 hours.
To serve, turn out the gelatin on plates and garnish as desired.