Zucchini Gratin with Corn and Bacon

The best dish to shine a spotlight on fresh summer produce! This cheesy zucchini gratin includes corn and sweet onions in a creamy sauce, plus gooey Gruyere cheese, crispy breadcrumbs, and smoky bacon on top.

The easy zucchini casserole is a simple side dish to serve with your favorite grilled chicken, salmon, or steak, but it’s also flavorful enough to stand on its own as an entrée with a side of crusty bread. If you have a bounty of zucchini in your garden, a delicious zucchini au gratin is the perfect way to enjoy it!

Zucchini au Gratin

While Zucchini Gratin or Zucchini au Gratin may sound fancy (thanks to its French name), this is really just a cheesy zucchini casserole! The word gratin means “a dish with a light browned crust of breadcrumbs or melted cheese,” and that’s exactly what we’ve got here. You’ll cook the onion, zucchini, and corn in butter and bacon drippings on the stovetop until tender, add flour and milk to make a creamy sauce, bake it in the oven, and finish it with Gruyere, homemade buttered breadcrumbs, and crispy bacon.

This easy recipe is a perfect summer side dish with fish or meat, or a light lunch or dinner when paired with a baguette. It’s truly the best way to eat your veggies this season!

The Bread Crumb Topping

Since buttered breadcrumbs are a hallmark of a good gratin, I prefer to make my own fresh bread crumbs for this recipe. Nothing can compare, and in this case it’s totally worth the extra few minutes of effort! A loaf of crusty sourdough yields a flavorful topping, but any rustic, hearty loaf will work.

To make ¾ cup fresh bread crumbs, start with about 1 ½ cups of cubed bread. Process the cubed bread in a food processor for about 30 seconds, or until it’s the consistency of coarse crumbs.

All of that said, you can certainly use a canister of store-bought breadcrumbs instead. To do so, choose either Panko breadcrumbs or Italian seasoned breadcrumbs for the best flavor and texture. Combine ¾ cup of the breadcrumbs with 1 tablespoon of melted butter.

What to Serve with Easy Zucchini Gratin

This rich, decadent, and easy zucchini casserole is a nice main course for lunch or dinner during the warm summer months. Pair it with a simple green salad dressed in balsamic vinaigrette and a side of crusty bread. We love this Dutch oven bread, this no-knead bread, or this easy baguette.

If you’d like to serve the zucchini au gratin as a side dish with a larger meal, try pairing it with any of these entrées:

• Grilled Salmon or Grilled Scallops
• Marinated Grilled Shrimp
• Grilled Chicken, Oven-Fried Chicken, Whole Roasted Chicken, or Roasted Chicken Thighs with Garlic and Herbs
• Grilled Flank Steak, Cast Iron Skillet Filet Mignon, or Grilled Steak Tips
• Grilled Pork Chops, Pork Tenderloin, or Pulled Pork
• Lemon Chicken Piccata, Pasta with Sausage and Spinach, or Shrimp Scampi

Zucchini Au Gratin Recipe Variations

• While fresh sourdough breadcrumbs are the best, you can substitute with store-bought Panko breadcrumbs or Italian breadcrumbs in a pinch. You can put the breadcrumbs on top of the gratin before it goes in the oven.
• I prefer fresh corn cut off the cob; however, you can substitute with frozen corn when necessary. If using frozen corn, you don’t need to add it to the skillet until the zucchini is almost tender, because the frozen corn will soften quickly.
• If you don’t have a cast iron skillet, pour the zucchini mixture into a 2-quart baking dish or other casserole dish before topping with cheese.
• Swap out the zucchini (or some of the zucchini) for yellow summer squash.
• If using regular bacon instead of thick-cut bacon, use 3 slices instead of just 2.
• If you prefer unsalted butter, just add an extra pinch or so of salt to the sauce.
• Any good melting cheese will work for this recipe, so feel free to substitute with cheddar, Swiss, or Gouda in lieu of the Gruyere.

Tips for the Best Zucchini Gratin Recipe

• Use a mandoline to quickly cut the zucchini and onion into even slices. You can see our favorite mandoline slicers here.
• Fresh corn cut off the cob is best for flavor and texture. I like to add some of the starchy liquid from the cob to the dish as well, which adds great flavor and helps to thicken the sauce a little bit.
• Use whole milk, half-and-half, or heavy cream — do not substitute with a lower fat alternative. You need the fat in the milk to create a thick, rich sauce.
• Garnish with fresh herbs like thyme, parsley, or chives for a bright and colorful finishing touch.

More Zucchini Recipes to Try

Garlic Parmesan Zucchini Casserole

40 minutes mins

Zucchini Banana Bread

3 hours hrs 5 minutes mins

Sautéed Zucchini

17 minutes mins

Looking for even more ideas? Check out this collection of 20 of the best zucchini recipes!

Zucchini Gratin with Corn and Bacon

Prep: 15 minutes minutes

Cook: 1 hour hour 5 minutes minutes

Resting Time 10 minutes minutes

Total: 1 hour hour 30 minutes minutes

Servings 6 people

Calories 336 kcal

A cheesy zucchini gratin with corn, bacon, and gruyere cheese is the perfect way to enjoy fresh summer produce!

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Ingredients

  

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BREAD CRUMB TOPPING:

• ¾ cup fresh bread crumbs*
• 1 tablespoon salted butter, melted

FILLING:

• 2 slices thick-cut bacon, chopped
• 4 tablespoons salted butter
• 1 medium onion, thinly sliced
• 1 lb. zucchini, sliced ¼-inch thick (about 2 zucchini)
• 2 cups fresh corn kernels (about 3 ears)
• 1 teaspoon kosher salt, plus more to taste
• Freshly-ground black pepper, to taste
• ¼ teaspoon ground nutmeg
• ¼ teaspoon garlic powder
• 2 tablespoons all-purpose flour
• 1 cup whole milk or cream, at room temperature
• ½ cup grated Gruyere cheese

Instructions

MAKE THE BREAD CRUMB TOPPING

• Preheat oven to 350°F. In a small bowl, toss together bread crumbs and melted butter. Spread on a baking sheet. Bake until lightly browned, about 4 minutes.
  

PREPARE THE FILLING

• In a 10-inch cast iron skillet (or other oven-safe skillet), cook bacon over medium heat until crisp, about 6-8 minutes. Use a slotted spoon to remove bacon to a paper towel-lined plate, reserving the drippings in the pan.
  
• Add the butter to the skillet with the drippings. When the butter melts, stir in the onion and cook over medium-low heat until softened, about 10-12 minutes.
  
• Add the zucchini and corn, cover with a lid, and cook until tender, about 10 minutes. Add the salt, pepper, nutmeg and garlic powder; cook uncovered for 1 more minute.
  
• Stir in the flour and cook for 1 minute. Gradually add the milk or cream, stirring constantly. Cook over low heat for 2-3 more minutes, or until the sauce comes together and thickens.
  
• Sprinkle the cheese over top.

BAKE

• Transfer the skillet to the 350°F oven. Bake (uncovered) for 20 minutes. Sprinkle buttered bread crumbs and bacon over top. Bake for 5 more minutes, or until the dish is bubbly.
• Let stand for about 10 minutes before serving.
  

Notes

*To make ¾ cup fresh bread crumbs, start with about 1 ½ cups of cubed bread (I like to use a crusty loaf of sourdough bread). Process in a food processor until the cubes are coarse crumbs.

• Use a mandoline to quickly cut the zucchini into even slices.
• Fresh corn cut off the cob is best for flavor and texture. I like to add some of the starchy liquid from the cob to the dish as well, which adds great flavor and helps to thicken the sauce a little bit.
• Use whole milk, half-and-half or cream — do not substitute with a lower fat alternative. You need the fat in the milk to create a thick, rich sauce.
• Garnish with fresh herbs like thyme, parsley or chives for a bright and colorful finishing touch.
• While fresh sourdough breadcrumbs are the best, you can substitute with store-bought Panko breadcrumbs in a pinch.
• I prefer fresh corn cut off the cob; however, you can substitute with frozen corn when necessary. If using frozen corn, you probably don’t need to add it to the skillet until the zucchini is almost tender, because the frozen corn will soften quickly.
• Swap out the zucchini (or some of the zucchini) for yellow squash.
• If using regular bacon instead of thick-cut bacon, increase it to 3 slices.
• Any good melting cheese will work for this recipe, so feel free to substitute with cheddar, Swiss, or Gouda in lieu of the Gruyere.

Nutrition

Serving: 1/6 of the recipeCalories: 336kcalCarbohydrates: 29gProtein: 11gFat: 21gSaturated Fat: 11gTrans Fat: 1gCholesterol: 49mgSodium: 710mgPotassium: 455mgFiber: 3gSugar: 8gVitamin A: 751IUVitamin C: 18mgCalcium: 203mgIron: 1mg

Keyword: zucchini au gratin, zucchini gratin

Course: Dinner, Lunch, Side Dish

Cuisine: American, French

Author: Blair Lonergan

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