Chef Juliette
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Filets de Merlan au Gratin
Created by Chef Juliette
Based on No. 1018, Filets de Merlan au Gratin, from Le Guide Culinaire (1907) by Auguste Escoffier
A complete gratin in one fierce bake: tender whiting, mushroom-lined sauce, white wine, and buttered crumbs all reach their proper finish at the same moment.
Main Dishes
French
Comfort Food
Dinner Party
25 min
Active Time
15 min cook•40 min total
Yield4 servings
Filets de Merlan au Gratin (whiting fillets baked beneath buttered crumbs) teaches the central law of the Complete Gratin (No. 269): the fish must cook, the sauce must reduce, and the crust must form at the same moment. That timing is the dish. Too much sauce leaves a watery bath beneath cooked fish; too little tightens before the fillets are ready.
The brigade version assumes a saucier on staff, stock never off the fire, a prepared sauce within the family of Gratins (No. 268), and a salamander waiting to finish the surface. At home, the linked sauce stays a finished component, the separate stock work stays in its own recipe, and a shallow gratin dish goes onto the upper rack of a fully heated oven. A brief broil supplies the salamander's direct heat only when needed. That is the scaffolding translated for four servings; the measured sauce, fierce heat, raw mushrooms, cooked mushroom caps, wine, crumbs, and generous butter remain because they are the dish. One cook, one stove, one evening.
Measure before you assemble. The fillets need a thin bed of sauce below and an even veil above, never a flood, with enough exposed surface for reduction. Getting that shallow layer right is the one step that matters most before the dish meets the oven.
Filets de merlan au gratin belongs to Parisian cuisine classique rather than to one named coastal province, although its modest whiting arrived from the Channel and Atlantic fisheries that supplied the capital's markets. Grand kitchens gave household gratins a precise system, matching the size of the fish, the quantity of sauce, and the force of the oven so cooking, reduction, and browning occurred together. Despite a common misconception, gratin does not mean cheese: here the proper crust comes from sauce, fine bread raspings, and butter.
The technique, the tradition, and the story behind every dish.
Discover Culinary ExplorerIngredients
skinless whiting fillets
Quantity
4 fillets, 5 to 5½ ounces each (about 600 g total)
pin bones removed
prepared gratin sauce
unsalted butter
Quantity
4 tablespoons (60 ml / 57 g)
divided
shallots
Quantity
3 tablespoons (45 ml / 30 g)
finely chopped
raw button mushrooms
Quantity
1½ cups (360 ml / 150 g)
thinly sliced
very small button mushrooms
Quantity
8 mushrooms (about 80 g total)
trimmed
dry white wine
Quantity
¼ cup (60 ml / 60 g)
fine fresh white breadcrumbs
Quantity
⅓ cup (80 ml / 30 g)
flat-leaf parsley
Quantity
2 tablespoons (30 ml / 8 g)
finely chopped
fresh lemon juice
Quantity
2 teaspoons (10 ml / 10 g)
fine sea salt
Quantity
¾ teaspoon (3.75 ml / 4.5 g)
freshly ground white pepper
Quantity
¼ teaspoon (1.25 ml / 0.5 g)
| Ingredient | Quantity |
|---|---|
| skinless whiting filletspin bones removed | 4 fillets, 5 to 5½ ounces each (about 600 g total) |
| prepared gratin sauce | 1 cup (240 ml / 250 g) for Gratins (No. 268) and Complete Gratin (No. 269) |
| unsalted butterdivided | 4 tablespoons (60 ml / 57 g) |
| shallotsfinely chopped | 3 tablespoons (45 ml / 30 g) |
| raw button mushroomsthinly sliced | 1½ cups (360 ml / 150 g) |
| very small button mushroomstrimmed | 8 mushrooms (about 80 g total) |
| dry white wine | ¼ cup (60 ml / 60 g) |
| fine fresh white breadcrumbs | ⅓ cup (80 ml / 30 g) |
| flat-leaf parsleyfinely chopped | 2 tablespoons (30 ml / 8 g) |
| fresh lemon juice | 2 teaspoons (10 ml / 10 g) |
| fine sea salt | ¾ teaspoon (3.75 ml / 4.5 g) |
| freshly ground white pepper | ¼ teaspoon (1.25 ml / 0.5 g) |
Equipment Needed
- •Shallow 12-by-8-inch (30-by-20-cm) broiler-safe gratin dish
- •Small skillet
- •Wide fish spatula
- •Instant-read thermometer
Instructions
- 1
Heat the oven
Set a rack in the upper third of the oven and heat it to 475°F (245°C) for at least 20 minutes. Butter a shallow 12-by-8-inch (30-by-20-cm) broiler-safe gratin dish with about 1 teaspoon of the butter. Bring the prepared gratin sauce for Gratins (No. 268) and Complete Gratin (No. 269) to a loose, spoonable consistency; if it has firmed in the cold, warm it gently with a spoonful of the measured wine, then let it become lukewarm. A cold, stiff sauce will not reduce evenly before the fish cooks.
- 2
Prepare fish and mushrooms
Run your fingertips over the whiting and remove any remaining pin bones. Blot the fillets thoroughly dry, then season both sides with most of the salt and all the white pepper. If the tail ends are markedly thinner, fold them underneath so every fillet cooks at nearly the same rate. Melt 2 teaspoons of the butter in a small skillet over medium heat, add the 8 whole mushroom caps with the remaining salt, and cook for 3 to 4 minutes, rolling them often, until glossy and just tender but still pale.
- 3
Assemble the gratin
Spread ¼ cup of the prepared gratin sauce for Gratins (No. 268) and Complete Gratin (No. 269) across the bottom of the buttered dish, then scatter over the shallots. Lay the fillets in a single layer without overlapping them. Surround the fish with the raw mushroom slices, keeping most of them beside rather than beneath the fillets, and place 2 cooked mushroom caps on each fillet. Pour the remaining wine around the fish, then spoon the remaining sauce over everything in a thin, even veil. Do not add extra sauce because the dish looks bare. The exposed breadth of this shallow layer is what lets it reduce on time.
- 4
Crumb and bake
Sprinkle the fine breadcrumbs evenly over the sauced fish. Melt the remaining butter and spoon it across the crumbs, moistening the entire surface. Bake immediately for 9 to 12 minutes, without repeatedly opening the door, until the crumbs are deep butter-gold, the sauce bubbles thickly at the rim without a watery ring, and the fish is opaque and reaches 140 to 145°F (60 to 63°C) at its thickest point. If the crust colors before the fish is ready, move the dish to the middle rack and shield the darkest areas loosely with foil. If the fish is cooked while the sauce remains thin, lift the fillets and their mushroom caps to a warm plate, reduce the surrounding sauce briskly in a wide saucepan for 1 to 2 minutes, return everything to the dish, and broil for 30 seconds to restore the crust. Ça se rattrape.
- 5
Finish and serve
Take the gratin from the oven and immediately scatter the chopped parsley over its bronzed surface. Drip the lemon juice evenly across the fish, using enough to sharpen the butter and mushrooms without turning the sauce sour. Carry the gratin dish directly to the table while its edges are still bubbling and serve each fillet with mushrooms and a generous spoonful of sauce. À table!
Chef Tips
- •Whiting is delicate, lean, and quick to cook, which is precisely why the sauce quantity matters. Ask for broad, evenly sized fillets. Thin hake or pollock can stand in at the same weight, but the result is a cousin of the dish rather than Filets de Merlan au Gratin.
- •Use a shallow dish that holds the fillets closely in one layer. A deep casserole traps too much liquid, while an oversized tray lets the sauce disappear before the fish is done.
- •The breadcrumbs must be fine fresh raspings, not coarse crumbs. Rub day-old white bread through a sieve or pulse it briefly, then stop before it becomes powder. Coarse crumbs brown in hard islands instead of joining the sauce and butter into one crust.
- •Serve with buttered spinach or plain boiled potatoes, something quiet enough to catch the sauce. A dry Muscadet or another brisk Atlantic white has the acidity for the butter, mushrooms, and lemon.
Advance Preparation
- •The prepared gratin sauce for Gratins (No. 268) and Complete Gratin (No. 269) can be made up to 2 days ahead and kept covered in the cold. Warm it only enough to become spoonable before assembly.
- •The shallots, parsley, and breadcrumbs can be prepared several hours ahead. Keep the parsley covered in the cold and the breadcrumbs dry at room temperature.
- •Cook the small mushroom caps up to 2 hours ahead, but do not combine the fish with wine, salt, or sauce until the oven is fully heated. Once assembled, the gratin must bake immediately.
Frequently Asked Questions
Nutrition Information
1 serving (about 245g)
Calories
380 calories
Total Fat
21 g
Saturated Fat
12 g
Trans Fat
1 g
Unsaturated Fat
8 g
Cholesterol
160 mg
Sodium
760 mg
Total Carbohydrates
14 g
Dietary Fiber
1 g
Sugars
3 g
Protein
33 g
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