Gratin of haddock with tomato sauce and spinach

This is a wonderful dish, an Annabel Karmel's recipe in Superfoods. Friends recently cooked this for lunch and everyone — four adults, two toddlers and two babies — just loved it. We ate it with baguette and butter.

Make ahead: I cooked the tomato sauce the night before and put the spinach in the fridge to thaw so it would be ready to go the day of cooking.

Gratin of haddock with tomato sauce and spinach
(adapted from Annabel Karmel's Superfoods)

1 Tbsp olive oil
1 onion, diced
2 cloves garlic, minced
1 400-mL can of diced tomatoes
1 1/2 tsp tomato paste
1/2 tsp sugar
1 bay leaf
1 Tbsp herbes de Provence
1 300-g package of frozen spinach, chopped
10 oz haddock (or other white fish fillets), skinned
2 Tbsp flour
2 Tbsp unsalted butter
1 1/2 cups cheddar cheese, grated

Preheat the oven to 350 F.

Heat the oil in a frying pan and saute the onion for five minutes until glassy and soft. Add the garlic and saute for two more minutes. Add the tomatoes, tomato paste, sugar, bay leaf and herbes de Provence. Bring to a boil and then turn the heat down and simmer, covered, for 15 minutes. Remove the bay leaf.

Thaw the spinach in the fridge. When thawed, take out a handful at a time and squeeze out the juice. (Chop up the spinach finely if using whole leaf.)

Put the flour in a large plastic freezer bag. Add the fish fillets and coat them in flour. Melt the butter in a frying pan and fry the fish for one-and-a-half minutes per side — seasoning each side with salt and pepper as you go — until lightly cooked.

Spread the spinach over the bottom of an ovenproof dish. Layer the fish fillets on top. Pour over the tomato sauce and sprinkle grated cheese over the top.

Bake for 10 minutes or until the fish is cooked all the way through.