Food / Main Dishes / Pescetarian

20-Minute Baked Flounder au Gratin

When, for a lack of a better term, “beginner fish people” come to me for advice on which fish recipes to start with, this Baked Flounder au Gratin always comes to mind first.

You just can’t go wrong with easy, crispy, parm-y, herb-y, and salty goodness.

When I started living the pescetarian lifestyle a few years ago, I decided that I didn’t want to force the lifestyle on my husband; I’d still cook him chicken or beef on the side and everything would work out swimmingly.

Or not.

Because hi. Cooking two meals every night is exhausting and what in the actual fuh… was I thinking.

So I was faced with a new challenge: how can I get him to genuinely enjoy fish? How can I not get him to confront me with a skeptical look when I tell him he’ll enjoy this dish?

A crispy coating and cheesy flavor can cajole just about anyone. Anytime in life. Always.

Baked Flounder Au Gratin | Killing Thyme

Flounder proved to be a fantastic fit for the au gratin style due to the fish’s mild flavor. But! If you can’t find flounder or if you’re devoted to another white fish like halibut, cod, or perch, go for it. The beautiful thing about most white fish is that they’re incredibly versatile and will adapt to most flavor profiles.

Though to be fair, I’ve whipped up a crispy salmon similar to this and it, too, is damn tasty. (That recipe can be found in my free eBook which you can download here!)

More good news: this recipe is ready in less than 30 minutes. So yeah, go ahead and chalk this up as one of your new go-o weeknight meals. It’s perfect for busy evenings when you want to fill up on something nutritious, but don’t have the time or energy to bring together a complex time-consuming feast.

If you make this dish, snap a photo and tag me on the Insta @killing__thyme! I love seeing your creations.

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5 from 8 votes

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!
Course Main Course
Cuisine Pescetarian
Prep Time 5 minutes
Cook Time 15 minutes
Total Time 20 minutes
Servings 4
Author Dana Sandonato


  • 4 6 oz flounder fillets any other white fish will do
  • 1/4 cup melted butter
  • 1 cup panko crumbs
  • 2/3 cups freshly grated Parmigiano Reggiano cheese
  • 1/2 tsp kosher salt
  • Cracked black pepper, to taste
  • 1 tsp dried thyme
  • Chopped fresh parsley, for garnish (optional)


  • Preheat the oven to 400° F.
  • Place the flounder fillets on a lightly oiled baking dish. Brush the tops of the fillets with 1 TBSP of melted butter.
  • In a small bowl, combine the panko bread crumbs, grated cheese, kosher salt, ground black pepper, and thyme. Add the rest of the melted butter to the crumb mixture and mix it 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 12-15 minutes, or until the fish is opaque, flakes easily with a fork, and reaches an internal temperature of 145° F.
  • This recipe goes great with a veg side, pasta, potatoes—pretty much anything!


  • Elena
    July 26, 2020 at 3:42 pm

    5 stars
    First time using a recipe off of this site and I have a huge love for flounder. It’s hard to find recipes that are creative with this fish so I was excited to make it. And omg it tasted amazing! i’m definitely keeping this recipe for a future date too because it was so simple :)

    • Killing Thyme
      July 26, 2020 at 4:45 pm

      Elena! I’m so glad you enjoyed this recipe. I’ve always enjoyed it, too. Thanks so much for taking the time to stop by with feedback and a rating!

  • Carmela Menichini
    September 24, 2019 at 8:52 pm

    5 stars
    This is a very delicious recipe and so quick and simple to prepare!

    • Jack Green
      October 23, 2019 at 5:04 pm

      5 stars
      This is the best recipe for flounder that I’ve tried. The couple I cook for are very picky about their food, specially their fish but they loved it my only regret I forgot to take a picture. 5 stars

      • Killing Thyme
        October 24, 2019 at 2:33 pm

        Jack! I’m so glad this recipe was a hit—especially for picky people :)
        As for pictures, there’s always next time ;)

  • Sarah
    March 21, 2019 at 6:31 pm

    5 stars
    My family LOVED this! Definitely a keeper!

    • Killing Thyme
      March 22, 2019 at 9:32 am

      I’m so glad, Sarah! Thanks for taking the time to pop by and let me know :)

  • Patti
    March 5, 2019 at 7:05 pm

    5 stars
    Definitely making this tonight, but gonna add a twist with a little mayo, a pinch of cayenne, dill and press on panko!!

    • Killing Thyme
      March 5, 2019 at 7:09 pm

      Sounds awesome, Patti! Let me know how it goes! :)

  • Toni
    January 13, 2019 at 4:05 pm

    Can your brrad the whole fish fillet and then bake it

    • Killing Thyme
      January 13, 2019 at 4:48 pm

      Hi Toni,
      You can definitely do that, though the breading beneath the fish might end up a bit soggy since it’s trapped beneath the fish and its moisture. If you have a cooling rack that fits your baking sheet, you could always try placing the rack on top of the baking sheet and placing the fillets on that. That way there’s air flow beneath the fillets.

  • Donna
    October 30, 2017 at 12:21 am

    I tried the Baked Flounder Au Gratin recipe and my entire family loved it! This will be enjoyed again very soon.

    • Killing Thyme
      October 31, 2017 at 8:05 am

      Hey Donna!

      I’m SO thrilled to hear this! I keep meaning to make this recipe again myself. The bummer about blogging about food is that I always feel pressure to make new things — thanks for reminding me that I need to make time to revisit some oldies :) And thanks so much for taking the time to stop by with feedback!

    • Jonny
      December 13, 2018 at 6:00 pm

      5 stars
      Omg just made this thanks so much

      • Killing Thyme
        December 13, 2018 at 6:22 pm

        So glad you enjoyed it, Jonny! Thanks for taking the time to leave some feedback :)

  • […] Baked Flounder au Gratin (Total time is 20 minutes): This dish is a perfect starting point. It’s easy to prep, it takes a measly 15 minutes to cook, it’s light in flavor and it offers up familiar flavors thanks to it’s cheesy and herbaceous golden crust. This recipe will work with any lightly flavored white fish, and it pairs wonderfully with Green Beans Almondine. […]

  • My Dish is Bomb
    March 11, 2016 at 3:14 pm

    So I actually never made the connection until now that flounder is a real actual fish. I would like to blame Disney and The Little Mermaid but I think my child brain probably thought I would never eat a character in a Disney movie. Child brain was so wrong, because this looks fantastic!

    • Killing Thyme
      March 11, 2016 at 5:10 pm

      It definitely isn’t spoken of TOO often, so don’t feel too bad ;)
      Just go into adult brain mode while making and eating this, and then go back to child brain mode. (Always go back to child brain mode!)


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