Equipment
Ingredients
Fish & Produce
- 400 g rockfish fillets, cut into bite-sized pieces
- 250 g fresh spinach, washed and tough stems removed
- 1 yellow onion, finely diced
- 2 garlic, minced
Dairy-Free Bechamel
- 45 ml olive oil
- 30 g all-purpose flour
- 400 ml unsweetened oat milk, room temperature
- 15 g nutritional yeast
- 5 g kosher salt
- 2 g black pepper, freshly ground
- 1 g ground nutmeg
Topping
- 40 g panko breadcrumbs
- 15 ml olive oil
Nutrition (per serving)
Nutrition is estimated per serving. Nutrients without complete source data are omitted.
Full nutrition
- Calories
- 417 kcal
- Protein
- 26 g
- Carbohydrates
- 32 g
- Fat
- 21 g
- Fiber
- 5 g
- Sugar
- 8 g
- Sodium
- 685 mg
- Saturated Fat
- 3 g
- Trans Fat
- 0 g
- Monounsaturated Fat
- 11 g
- Polyunsaturated Fat
- 2 g
- Cholesterol
- 50 mg
- Potassium
- 1044 mg
- Calcium
- 347 mg
- Iron
- 3.2 mg
- Magnesium
- 88 mg
- Phosphorus
- 276 mg
- Zinc
- 1.0 mg
- Vitamin A
- 297 mcg
- Vitamin C
- 21 mg
- Vitamin D
- 3.8 mcg
- Vitamin E
- 3.8 mg
- Vitamin K
- 313 mcg
- Vitamin B6
- 0.4 mg
- Vitamin B12
- 1.4 mcg
- Thiamin
- 0.20 mg
- Riboflavin
- 0.37 mg
- Niacin
- 3.7 mg
- Folate
- 150 mcg
- Water
- 173 g
Sources: Aggregated Public Data, USDA FoodData Central
Method
Preheat your oven to 200°C/400°F.
Heat 15ml of olive oil in a large oven-safe skillet over medium heat. Add the diced yellow onion and minced garlic, sauteing until softened and translucent.
Add the fresh spinach to the skillet in handfuls. Cook until completely wilted and all released water has evaporated to prevent a watery gratin.
Push the cooked vegetables to the edges of the skillet. Pour the remaining 30ml of olive oil into the center, then sprinkle the all-purpose flour over the oil. Stir the flour and oil together to form a paste, cooking briefly to toast the raw flour.
Gradually whisk the room temperature oat milk into the flour paste. Continuously whisk until smooth, then stir the vegetables back into the center to combine everything.
Stir in the nutritional yeast, kosher salt, black pepper, and ground nutmeg. Simmer the mixture until it thickens enough to coat the back of a spoon.
Remove the skillet from the heat. Gently fold the bite-sized rockfish pieces into the thickened sauce, ensuring the fish is evenly distributed. Wash your hands and any surfaces immediately after handling the raw fish to prevent cross-contamination.
In a mixing bowl, toss the panko breadcrumbs with 15ml of olive oil until evenly moistened. Sprinkle this mixture in an even layer over the top of the skillet.
Transfer the skillet to the preheated oven. Bake until the sauce is bubbling, the crust is golden brown, and the fish reaches a safe internal temperature of 63°C/145°F.
Remove the gratin from the oven and let it rest before serving. This allows the sauce to set up properly and prevents it from being too runny on the plate.
Chef's Notes
- Rockfish cooks quickly, so cutting it into uniform chunks ensures even cooking without drying out in the oven.
- Unsweetened oat milk provides the most neutral, creamy base for a dairy-free bechamel, but always check the label for hidden vanilla or sugars.
- Nutritional yeast mimics the savory, umami-rich profile of traditional Gruyere or Emmental cheese used in classic French gratins.
- For a truly one-pot experience, making the roux directly in the center of the pan pushes the flavors of the sauted aromatics directly into the sauce.
- When handling raw rockfish, ensure you use a dedicated cutting board to avoid cross-contamination with the fresh spinach and other ready-to-eat ingredients.
Storage
Refrigerator: 3 days — Cover tightly to prevent fish odors from permeating the refrigerator.
Freezer: 1 month — Can be frozen, though the panko topping will lose its crispness upon thawing.
Reheating: Reheat in a 175C oven until bubbling to restore the crust texture.
Troubleshooting
Sauce is too thin and watery after baking
Cause: Spinach was not cooked down enough before adding liquids, or fish released excess moisture.
Fix: Simmer the gratin on the stovetop for a few extra minutes before baking to reduce the liquid, though after baking it cannot be fully corrected without overcooking the fish.
Prevention: Ensure all water from the spinach evaporates before making the roux. Pat fish dry before adding to the skillet.
Cultural Context
The gratin technique originated in French cuisine, typically relying heavily on cream, butter, and cheese to achieve its signature rich texture. This modernized, dairy-free adaptation utilizes plant-based emulsification techniques to replicate the comforting mouthfeel of a classic gratin while remaining accessible for diverse dietary requirements. Incorporating fresh rockfish transforms a humble side into an elegant, satisfying dish worthy of a New Year's Day celebration.
