Flounder Au Gratin

Prep: 15 min Cook: 25 min Serves: 4 Cuisine: American

Creamy flounder au gratin features tender fillets topped with a Swiss cheese sauce, perfect for a comforting seafood dinner that appeals to family and friends alike.

Be the first to rate this recipe

Ingredients

  • 1 Tbsp. margarine
  • 4 green onions
  • 2 Tbsp. diced celery
  • 2 tsp. all-purpose flour
  • 1/2 tsp. salt
  • 1/8 tsp. white pepper
  • 1/2 cup skimmed milk
  • 1/4 cup shredded Swiss cheese
  • 1 (16 oz.) package frozen flounder fillets
  • 1 Tbsp. fresh parsley

Instructions

  1. Melt margarine in a small saucepan over low heat.
  2. Add green onions and diced celery; sauté until tender.
  3. Stir in flour, salt, and white pepper; cook for 1 minute, stirring constantly.
  4. Gradually add skimmed milk; stir well and cook over medium heat until thick and bubbly.
  5. Add shredded Swiss cheese; reduce heat and cook until cheese melts, stirring constantly.
  6. Set aside the cheese sauce.
  7. Arrange thawed and drained flounder fillets in a single layer in a 10 x 6 x 2-inch baking dish coated with vegetable cooking spray.
  8. Pour the cheese mixture evenly over the fillets.
  9. Cover and bake at 350°F for 25 minutes, or until fish flakes easily.
  10. Sprinkle with minced parsley before serving.

Tips & Substitutions

For a richer flavor, consider substituting the skimmed milk with half-and-half or whole milk. If you prefer a different cheese, Gruyère or cheddar can also work well in this recipe. To save time, use pre-chopped vegetables or frozen diced celery and onions. Additionally, keep an eye on the cheese sauce to prevent it from burning while cooking.

Serving Suggestions

Flounder au gratin pairs beautifully with a side of steamed vegetables or a fresh green salad to balance the richness of the dish. Consider serving it alongside garlic bread or a light pasta with olive oil for a complete meal. For a delightful contrast, enjoy it with a chilled white wine or a light beer.

Storage & Reheating

Store any leftovers in an airtight container in the refrigerator for up to 2 days. To reheat, place the flounder au gratin in a baking dish and cover with foil, heating in a preheated oven at 350°F until warmed through, about 15-20 minutes. Avoid microwaving, as it can make the fish rubbery.

Nutrition & Diet Analysis (per serving)

Each serving of Flounder Au Gratin contains roughly 1014 calories, with 37g protein, 136g carbohydrates, and 43g fat. It is an excellent source of iron (163% of the Daily Value), vitamin C (160% of the Daily Value), and calcium (126% of the Daily Value), and a good source of vitamin D. Note that it is relatively high in sodium, at 2514mg per serving (109% of the Daily Value).

1014 kcal 51% DV
Protein Fat Carbs

Macronutrients

Protein 37.1g 74% DV
Total Fat 43.3g 55% DV
Carbs 136.4g 50% DV
Fiber 27.6g 99% DV
Sugar 59.6g 100% DV

Electrolytes

Sodium 2514.3mg 100% DV
Potassium 3028.1mg 64% DV
Cholesterol 15.9mg 5% DV

Vitamins & Minerals

Vitamin A 322.7mcg 36% DV
Vitamin C 144mg 100% DV
Vitamin D 2.4mcg 12% DV
Calcium 1639.8mg 100% DV
Iron 29.3mg 100% DV
Diet fit High-protein High-fiber
Contains Milk Wheat/Gluten

Estimated from ingredients & per-serving nutrition — verify against package labels for allergies or strict diets.

* % Daily Values based on a 2,000 calorie diet (FDA 2020).

Frequently Asked Questions

Can I use fresh flounder instead of frozen?

Yes, fresh flounder can be used instead of frozen. Just ensure that it is properly thawed and patted dry to avoid excess moisture. Fresh fish may cook slightly faster, so keep an eye on it while baking to ensure it doesn't overcook.

What can I substitute for Swiss cheese?

If you don’t have Swiss cheese on hand, you can substitute it with Gruyère for a similar flavor profile. Cheddar also works well for a sharper taste, though it will slightly change the flavor of the dish. Feel free to mix different cheeses for a unique twist.

How can I make this dish gluten-free?

To make Flounder Au Gratin gluten-free, simply replace the all-purpose flour with a gluten-free flour blend or cornstarch as a thickening agent. Ensure that the cheese and other ingredients are certified gluten-free, especially if you are serving someone with celiac disease or gluten sensitivity.

Nutrition is estimated from USDA FoodData Central ingredient data and may vary with brand, portion and preparation — see our methodology. This information is for general educational purposes only and is not medical or dietary advice (disclaimer).

American recipes → Seafood recipes → Dairy recipes → All recipes →