Place the unpeeled onions in a pan, cover with water and boil uncovered for 30 min.
Drain and cool the onions, trim off the root and peel off the very outer skins.
Slice off top and reserve for later.
Preheat oven to 180 C Using a teaspoon, hollow out the centres so you are left with 2 thick layers of the shell.
Chop up the insides of the onions and reserve for later.
Place olive oil in a saucepan and add the spinach, garlic and parsley and cook gently for 4 min.
Drain and squeeze out the excess moisture.
Place in a bowl and add the chopped onion.
To make the sauce, place the sachet contents and the milk in a saucepan.
Heat stirring until the mixture thickens.
Spoon the spinach mixture into the onions.
Pour the sauce around the onions, pop the reserved tops onto the onions and bake in a preheated oven at 180°C for 20 min.
Season with Black pepper and serve