Pre-heated oven at 170 degrees C.
Preparing the fish fillets: Season the fillets with salt and pepper and a squeeze of lemon juice.Place onto a lightly buttered baking sheet or oven proof dish flesh side down and bake for 8-10 minutes. Remove the fish from the oven you should be able to peel the skin of easily. Place the cheese crust  on each of the fillets and return to the oven until golden brown approx 3-4 mins. Place under a grill if necessary.
To make the cheddar crust:Mix the breadcrumbs cheddar and butter add a little lemon juice and cracked black pepper- the mix should be dry and hold shape when pressed slightly. 
Cooking the spinach:Place in a microwave bowl season lightly with salt and pepper  and cook for 1 to  2mins at high heat and  drain of  excess juices add the béchamel, check your seasoning and reheat.
To Serve:Warm two plates. Place the spinach in the centre of both plates set the fillets of fish on top. Serve with lemon on the side.