Smoked Haddock Gratin

haddock 28.0% , milk 15.9% , potato 15.2% , cream 13.0% , cheddar 10.0% , spinach 8.3% , crème fraîche 4.8% , breadcrumbs 2.4% , butter 1.2% , onion 0.6% , white wine 0.3% , wheat flour 0.1% , parsley 0.1% , rapeseed oil 0.0% , lemon juice 0.0% , dill 0.0% , fish stock 0.0% , garlic puree 0.0% , white pepper 0.0% , salt 0.0%