Fish Florentine Baked White Fish with Gruyère Mornay

Elevating Dinner: Why This Fish Florentine Recipe Always Wins

Listen, I used to think Fish Florentine was one of those dishes you only ordered in a fancy, dimly lit Italian restaurant. Then I tried making it at home using a standard skinny taste fish florentine recipe, which mostly used cottage cheese and shame. It was... fine.

But it wasn’t the showstopper. It definitely wasn't the incredibly creamy, bubbling, golden and crusted dish of pure comfort I truly wanted.

This version? This is the one. It looks super elegant, like you spent hours stirring, but honestly, it’s done and dusted in under an hour. The secret isn't in some expensive ingredient; it’s in two specific techniques: mastering the cheese sauce and aggressively removing water from the spinach.

Follow my lead, and you'll never have a disappointing, watery fish casserole again. This is proper, old and school comfort food.

Decoding the French Technique: Gruyère Mornay Magic

When you see "Florentine" paired with any protein (chicken, eggs, fish), it means spinach and a creamy sauce. In classic French cooking, a creamy white sauce is Béchamel (milk, butter, flour).

When you take that Béchamel and stir in cheese, specifically Gruyère or a good strong cheddar, it stops being Béchamel and becomes a Mornay. See? Fancy.

We’re using Gruyère because it melts like a dream, has this lovely nutty depth, and pairs beautifully with the delicate flavor of white fish. Don't even think about using low and fat, pre and shredded mozzarella here. We are aiming for luxurious, not rubbery.

The 'Florentine' Element: Sautéing Spinach to Perfection

The "Florentine" part is just a fancy way of saying "with spinach." But here is where 90% of home cooks fail and end up with a soupy, bland mess. Spinach is 90% water. If you just wilt it and chuck it in your baking dish, that water will steam out in the oven, diluting your gorgeous Mornay sauce right into a watery, milky puddle.

Ugh.

CRUCIAL WARNING: After you sauté your spinach, you absolutely must, MUST squeeze it dry. Use a sieve and the back of a spoon, or, my favorite trick, put the wilted spinach into a clean kitchen towel and wring it out like you’re trying to impress someone with your forearm strength.

It needs to be dry. Bone dry.

Essential Components for Your Kitchen Prep

Selecting the Best White Fish Fillets (Cod vs. Haddock)

When I’m making this white fish florentine , I always grab either Cod or Haddock. They are both excellent choices, but they behave differently.

Fish Type	Texture & Flavor Profile	Best For...
Cod	Mild flavor, very thick, tends to flake into large, tender pieces.	Classic elegance and maximum moisture.
Haddock	Slightly firmer texture, holds its shape a bit better than cod, subtly sweeter.	Casseroles where you want definition.

If you’re using frozen fish fillets florentine style, that’s fine! Just make sure they are completely thawed and, most importantly, patted totally dry before seasoning. Otherwise, they release even more water.

Pantry Check: Ingredients for a Lumpy and Free Béchamel

We are striving for silky smoothness. That means you need fresh ingredients, especially the flour and milk. Make sure your milk is warm . Not boiling, but warm enough that when you add it to the hot butter and flour roux, you don't shock the mixture.

Also, grating your own Gruyère cheese is a non and negotiable step. Pre and shredded cheese is coated in starches that can make your sauce gritty. We want velvety, flowing sauce, not something that feels like sand has been added.

Required Kitchen Utensils for Seamless Baking

Honestly, this recipe isn't fussy, but you absolutely need two things:

• A sturdy whisk: For building the Béchamel. You need to whisk aggressively, especially when incorporating the milk. I’ve broken flimsy whisks doing this.
• A good, deep 9x13 inch baking dish: This dish is rich. You want some space around the fish so the sauce can bubble up happily without spilling all over your oven floor (I speak from experience, sadly).

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Step and by-Step Guide to Perfectly Baked Fish Florentine

Preparing the Florentine Base and Draining Excess Moisture (Crucial Step!)

Right then. Get your garlic and butter sizzling in the big skillet. Add your mountain of fresh spinach. It looks ridiculous at first, right? Like there’s no way it will fit. But it wilts down in about two minutes.

Add a small pinch of nutmeg here it's optional, but it gives the spinach this warmth that really sings against the creamy sauce.

Once wilted, transfer that spinach to a colander. I mean it. Push down on it. Really push. You should see pools of green liquid draining out. That liquid is the enemy of creamy easy fish florentine dinner . When you think it’s dry enough, squeeze it one more time for good measure.

Spread that dried spinach base evenly in your greased baking dish.

Building the Gruyère Mornay: Achieving a Silky Smooth Texture

This is the only part that requires your full attention. We start with the roux: equal parts butter and flour melted together. Cook it for a minute or two until it smells nutty, like popcorn. This removes the raw flour taste.

Now for the milk. Take the saucepan off the heat for a minute. Add the warm milk slowly , about half a cup at a time, whisking vigorously. It will look like a thick paste at first, then a slurry. Keep whisking and keep adding until all the milk is incorporated and the sauce is smooth and lump and free.

Then, put it back on medium heat, stirring until it thickens enough to coat the back of a spoon.

Remove it from the heat again and immediately stir in your grated Gruyère. That residual heat is enough to melt it perfectly. Taste it. Does it need more salt? White pepper is traditional, but I sometimes sneak a pinch of cayenne in there for a subtle kick.

Assembling the Casserole and Final Cheese Layer

Pat your fish fillets dry again (just in case they wept a little) and place them on top of the squeezed spinach base. Now, pour that incredibly creamy Mornay sauce over everything. Make sure the fish is covered. We want those edges to bubble and brown.

Finally, a sprinkle of Parmesan on top ensures a beautifully golden, crackling crust. That's the best part, right?

Oven Time: Baking Until Golden and Bubbly

Slide that dish into your preheated 400°F (200°C) oven. Baking usually takes about 18 to 22 minutes. You are looking for two things: The sauce should be actively bubbling around the edges, and the top needs to be a rich, golden brown.

Most importantly, the fish should flake easily when poked with a fork. Don't overcook it! Overcooked fish is sad.

Advanced Tips and Troubleshooting Your Dish

Solving Common Issues: Why Did My Béchamel Sauce Break? (Q&A)

This happens to everyone. Usually, a broken sauce (where the fat separates and it looks curdled) is due to too much heat or adding cold liquid too fast.

If your sauce breaks: Take it immediately off the heat. Grab a separate small bowl and whisk 1 tablespoon of cold milk with 1 teaspoon of flour until smooth. Slowly drizzle this slurry into your broken sauce while whisking furiously. This can often re and emulsify the mixture. If not, don't panic!

Just pour it over the fish anyway; once it bakes, the flour and cheese will often redistribute and tighten up.

Making Ahead and Storage: Freezing Instructions

• make-ahead: This is a perfect make and ahead meal! Assemble the entire casserole (up to the point of baking), cover it tightly, and refrigerate for up to 24 hours. When you're ready to bake, add 5– 10 minutes to the total baking time since it’s starting cold.
• Freezing: Yes, you can freeze Fish Florentine, but the texture will change slightly. The sauce can get a little grainier upon thawing due to the dairy. Assemble, cover well with foil, and freeze for up to 2 months. Thaw overnight in the fridge before baking.

Serving Suggestions: What Sides Pair Best with This Rich Dish?

This elegant seafood recipe is intensely rich because of the cream and cheese. You need something acidic or very plain to cut through that richness.

• A simple, fluffy grain like basmati rice or couscous.
• Roasted asparagus or crisp green beans tossed simply in lemon juice and olive oil.
• A salad with a sharp, vinegar and based vinaigrette (no creamy dressings, please!).

Speedy Substitutions and Swaps for the Cheeses

I know Gruyère can be pricey or hard to find. If you’re rushing and need a quick swap:

• For Gruyère: Use Jarlsberg (great melt, similar nuttiness), sharp white Cheddar (adds tang), or Monterey Jack (excellent melt, very mild flavor).

Adjusting for Dietary Needs (Gluten and Free Roux Option)

You absolutely can make this gluten and free without sacrificing the luxurious texture. Instead of using all and purpose flour for the roux, use rice flour or a standard gluten and free all and purpose blend.

Alternatively, you can thicken the sauce at the end using a cornstarch slurry (1 tbsp cornstarch mixed with 2 tbsp cold water), whisked into the hot Béchamel. The resulting sauce might be slightly shinier, but the flavor will be exactly the same. Go forth and cook!

Recipe FAQs

What exactly is Fish Florentine? Is it just fish and spinach?

The 'Florentine' bit simply means the dish includes spinach, typically sautéed with butter and garlic. This classic Fish Florentine dish is elevated by the rich Mornay sauce a creamy Béchamel enriched with Gruyère cheese making it a real crowd pleaser and a proper sophisticated supper.

My baked fish dishes always turn out watery. How do I stop the spinach base from ruining the sauce?

That’s a classic problem! The absolute key is wringing the moisture out of the spinach until it’s drier than the Sahara, ideally using a clean tea towel, otherwise, the excess liquid will absolutely weep into your beautiful Mornay sauce during baking and make everything soggy.

I haven't got Cod on hand. Can I use Salmon or something else firm for this recipe?

Absolutely! While Cod, Haddock, or Halibut are traditional choices because they are flaky, sturdy white fish like Tilapia or even Monkfish work a treat. Just bear in mind that using a fattier fish like Salmon will slightly change the flavour profile, but it’s still perfectly delicious.

Help! I've gone and made a lumpy Béchamel sauce. Is there any saving it?

Don't chuck it out just yet! Lumps are often caused by adding cold milk to a hot roux too quickly, but the trick to fixing it is taking it off the heat and giving it a serious blitz with an immersion blender, or pushing it through a fine mesh sieve a bit of elbow grease and it will be smooth as silk again.

Can I assemble this ahead of time, or is it better to bake it straight away?

You can certainly get ahead of the game, which is brilliant for dinner parties! Assemble the dish completely, cover it tightly, and refrigerate for up to 24 hours; just be sure to allow it to come to room temperature for about 20 minutes before baking, and add 5-10 minutes to the cook time.