Warm the cream in a medium-sized pot set over a medium heat, then add the baby spinach, garlic, nutmeg and a pinch of salt and pepper. Cook for 1 to 2 minutes, until the spinach has wilted down.
Place the cream cheese, half of the breadcrumbs and the lemon juice in a medium mixing bowl and mix well.
Spread the cooked spinach and cream over the base of a baking dish. Lay the fish on top and cover with the cream cheese mixture.
Mix the remaining breadcrumbs with the lemon zest, parsley and some salt and pepper, then sprinkle this over the fish. Bake for 12 to 15 minutes, until the fish is cooked through and the breadcrumbs are golden.