This baked flounder recipe is the perfect weeknight meal. It’s easy, wholesome, and ready in just 20 minutes!

Crispy golden baked flounder on a white speckled serving plate, garnished with fresh parsley.

New to Fish? Start With a Baked Flounder Recipe.

Whether you’re new to eating fish or cooking it—or both—this baked flounder au gratin is the perfect starting point. Flounder is a very mild white fish with a flaky texture and a clean flavor; it’s not fishy at all! And the crispy topping adds a pop of extra flavor with thyme and parmesan, making it easy for newbies to enjoy. Easy to prep and cook, this flounder takes about 20 minutes to bring together and pairs with most veg and starch sides. So, if you’re looking to incorporate more fish into your diet, this is a fantastic starting point.

For more useful info, check out my Fish & Seafood Guide.

Ingredients to Add to Your Shopping List.

  • Flounder fillets
  • Olive oil
  • Panko breadcrumbs
  • Parmigiano Reggiano cheese
  • Sea salt
  • Cracked black pepper
  • Fresh parsley
  • Lemon wedges

Raw flounder fillets on top of Butcher's paper with olive oil, a bowl of breadcrumbs, bowl of grated parm, salt crock, herbs, and pepper mill.

How to Bake Flounder.

Baking fish can be nerve wracking because it overcooks so easily, and once fish is overcooked, it’s impossible to enjoy. Flounder fillets aren’t thick like salmon or sea bass, so you want to keep a close on eye on it if you’re new at cooking fish. Here’s how to make this baked flounder recipe:

  1. Preheat the oven to 400° F.
  2. Put the flounder onto a parchment-covered sheet pan or lightly oiled baking dish and gently blot them with a paper towel to absorb excess moisture.
  3. Let the fillets come to room temperature—this should take about 15 minutes. This will help you get a more even cook.
  4. Hit the fillets with a sprinkle of salt and pepper, then brush the tops of the fillets with olive oil.
  5. Combine the panko breadcrumbs, grated cheese, a pinch of salt, and dried thyme in a small mixing bowl. Then add the rest of the olive oil to the crumb mixture, and mix it with a fork until the crumb mixture becomes buttery, crumbly, and golden.
  6. Sprinkle the crumb mixture over the fillets and lightly press the crumbs down onto the fillets.
  7. Bake the fish for 10-12 minutes. The fish should be opaque, flake easily with a fork, and have an internal temperature of 145° F.
  8. Finish the fillets off with some freshly chopped parsley and serve with lemon wedges for spritzing.

Two overhead shots of flounder fillets on baking sheet; one shot unbreaded, the other breaded.

Useful Tools for This Recipe:

Recipe tips + tricks.

  1. For a little extra indulgence, use melted butter instead of olive oil.
  2. This recipe works with any white fish fillets, though cooking time will vary. Thicker fillets will take a bit longer.
  3. Italian breadcrumbs will work in place of panko.

Have You Made This Recipe?

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Sides to Serve With This Baked Flounder Recipe:

Baked Flounder Au Gratin | Killing Thyme

Side close up of baked flounder au gratin on serving plate.

Side close up of baked flounder au gratin on serving plate.

Get the Recipe:

20-Minute Baked Flounder au Gratin

This crispy and flavorful Baked Flounder Au Gratin is the perfect weeknight meal. It's easy, wholesome and ready in 20 minutes!
5 from 24 votes

Ingredients

  • 4 6 oz flounder fillets, No flounder? You could use any white fish for this recipe.
  • 2 TBSP extra virgin olive oil, divided
  • 1 cup panko breadcrumbs
  • 2/3 cups freshly grated Parmigiano Reggiano cheese
  • 1/2 tsp kosher salt
  • A few grinds of cracked black pepper
  • 1 tsp dried thyme, You could also use a dried Italian herb mix
  • Chopped fresh parsley, for garnish
  • Lemon wedges, for serving

Instructions 

  • Preheat the oven to 400° F.
  • Place the flounder fillets on a parchment-covered sheet pan or lightly oiled baking dish. Lightly blot them with a paper towel to absorb excess moisture and let the fillets come to room temperature by leaving them out for about 15 minutes before placing them in the oven. (This will help you get a more even cook.) Season the fillets with a sprinkle of salt and pepper, then brush the tops of the fillets with 1 TBSP of the olive oil.
  • In a small bowl, combine the panko breadcrumbs, grated cheese, a pinch of salt, and dried thyme. Add the rest of the olive oil to the crumb mixture and mix with a fork until the crumb mixture becomes buttery, crumbly, and golden in color.
  • Sprinkle the crumb mixture over the fillets and lightly press the crumb mixture down into the fillets.
  • Bake the fish for 10-12 minutes, or until the fish is opaque, flakes easily with a fork, and reaches an internal temperature of 145° F.
  • Garnish with freshly chopped parsley and serve with lemon wedges for spritzing.
Calories: 439kcal, Carbohydrates: 3g, Protein: 32g, Fat: 9g