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Summer Squash Gratin

Summer Squash Gratin is yet another way to enjoy the abundance of summer squash and zucchini. Topped with a buttery crumb topping, it’s a spectacular side dish to make.
baked Summer Squash Gratin

Summer Squash Gratin

When Summer produce starts arriving, it seems like there’s an endless stream of yellow squash and zucchini. I love them both regardless of how they’re prepared, and not just in the Summer.  This squash gratin, has a creamy homemade cheese sauce reminiscent of the same you might use with macaroni and cheese.  That alone qualifies this dish as “Comfort Food: 101.” The crispy topping can be made with any flavor of cracker that you like providing the crispy texture to the cream sauce.

ingredients to make Summer Squash Gratin recipe


Helpful Tips for Making Squash Gratin

  • You can use a combination of yellow squash and zucchini or one or the other for this recipe.
  • You can easily adapt using any variety of cheese that you enjoy or have on hand.
  • This dish can also be fully prepped and assembled in advance, then topped with the cracker topping just before baking for a time saver.  It’s yet another way to enjoy farm stand goodness at your own kitchen table.
  • Other squash recipes to try: Creole Squash Cakes, Italian Sausage Stuffed Summer Squash and Squash Fritters. 
  • You may also enjoy these Summer Vegetable Kabobs from Southern Living.
summer squash casserole recipe

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Summer Squash Gratin

Prep Time20 minutes
Cook Time40 minutes
Total Time1 hour
Servings: 8 servings
Calories: 470kcal
Author: Melissa Sperka


  • 1 1/2 lb zucchini 1/4" slices
  • 1 1/2 lb yellow squash 1/4" slices
  • 1 medium sweet onion small dice
  • 1/2 cup butter plus 2 Tbsp divided
  • 1 Tbsp Dijon mustard
  • 1/3 cup all purpose flour
  • 1 tsp salt
  • 1/2 tsp white or black pepper
  • 1/2 tsp garlic powder
  • 3 cups milk
  • 3 cups shredded sharp cheddar cheese divided [white or yellow]
  • 1 sleeve Ritz crackers crushed [I used Ritz Roasted Vegetable]


  • Preheat the oven to 350°F. Spritz an 9 x 9 deep dish baking dish or an 8 x 12 inch oblong dish with cooking spray.
  • Steam the sliced zucchini and yellow squash until fork tender, around 7-8 minutes. Drain and cool slightly.
  • In a heavy bottomed saucepan, cook the diced onion in 1/2 cup of butter.
  • Cook over medium high heat until soft, around 3 minutes. Add the Dijon mustard, all purpose flour, salt, pepper and garlic powder. Whisk over medium heat until combined.
  • Gradually add the milk, whisking constantly. Bring to a boil, then lower the heat and gently bubble for 5 minutes until thickened.
  • Add 1 cup of shredded cheese to the sauce and stir until melted.
  • To assemble: Layer half of the steamed squash into the bottom of the dish. Season lightly with salt and black pepper to your taste. Cover with 1/2 of the sauce and sprinkle with 1 cup of shredded cheese.
  • Repeat layers: Last layer of squash, salt & black pepper, remaining sauce, then ending with 1 cup of shredded cheese.
  • Melt 2 Tbsp of butter and toss with the cracker crumbs. Spread on top.
  • Bake for 35-40 minutes until golden and bubbly.


Serving: 1serving | Calories: 470kcal | Carbohydrates: 28g | Protein: 17g | Fat: 34g | Saturated Fat: 18g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 8g | Trans Fat: 1g | Cholesterol: 84mg | Sodium: 858mg | Potassium: 670mg | Fiber: 2g | Sugar: 12g | Vitamin A: 1269IU | Vitamin C: 32mg | Calcium: 449mg | Iron: 1mg
Tried this recipe?Mention @melissassk or tag #melissassk!



  1. This is absolutely DELICIOUS!!!! I’ve made a few times now. The last time I added some green beans, can of asparagus, peas and corn just to see how it would be and its awesome that way too. Thank you for the recipe.

  2. Melissa, great recipe! And super new look for the blog. I’m able to do all the viewing (noticed today that when I was viewing it before, the top portion was cut off). All is well now and I’m thrilled:)

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