Defrost the spinach in the microwave (4 minutes on high), then squeeze out excess water.

Make Egg mixture: Place ingredients into a bowl and whisk until combined.

Spread half the bread into the base of a baking dish 25cm x 25cm (10" x 10").

Layer with the spinach, then chicken then top with half the cheese.

Top with remaining bread. Squish the bread down to compress (this helps the egg mixture to be soaked up evenly).

Pour over egg mixture - try to cover all the bread evenly.

Top with remaining cheese, then squish down to help the bread soak up the egg mixture.

Set aside for at least 15 minutes, preferably 30 minutes.

To freeze: Cover tightly and place in freezer. Defrost completely before cooking.

Preheat oven to 180C/350F.

Cover baking dish with foil and bake for 20 minutes. Remove foil, then bake for a further 10 minutes until golden on top.

Serve immediately, sprinkled with parsley if desired.