Why You’ll Love This Zucchini and Yellow Squash Au Gratin

Hey there, fellow food lovers! Are you ready for a side dish that’s as gorgeous as it is delicious? This creamy dreamy zucchini and yellow squash au gratin is about to become your new obsession. Forget bland, boring squash – this recipe transforms these summer vegetables into a comforting, cheesy masterpiece. Imagine tender zucchini and yellow squash bathed in a rich, creamy sauce, topped with a glorious layer of melted Gruyère. The taste? Simply divine! A beautiful blend of savory, cheesy, and subtly sweet, it’s the perfect balance of flavors. The texture? Perfectly tender squash with a delightful, slightly crisp top. And the best part? It’s surprisingly quick and easy to make!

This recipe is perfect for those summer nights when you want something fresh, yet comforting. It’s the ideal side dish for grilled meats, roasted chicken, or even a simple pasta dish. But let’s be honest, it’s so good, it could easily be a vegetarian main course! The vibrant yellow and green colors make it a stunning addition to any dinner table, instantly elevating the mood and making everyone feel special. You’ll love the ease of preparation, the incredible taste, and the undeniable satisfaction of creating something so delicious with simple ingredients.

So, gather your ingredients, put on some feel-good music, and get ready to experience the magic of this zucchini and yellow squash au gratin. Trust me, your taste buds will thank you!

What You’ll Need

Here’s what you’ll need to create this cheesy, dreamy side dish. I’ve included little notes on why each ingredient is important, so you can appreciate the magic we’re about to create!

2 medium zucchinis, thinly sliced: The star of the show! Choose firm, fresh zucchinis for the best texture.
2 medium yellow squashes, thinly sliced: Adds beautiful color and a slightly sweeter note compared to zucchini.
1 tbsp olive oil: Provides a lovely flavor base and helps to sauté the onions and garlic.
1/2 cup diced onion: Adds a subtle sweetness and depth of flavor. Feel free to use your favorite type of onion, such as yellow or white.
2 cloves garlic, minced: A touch of pungent garlic is key to enhancing the overall flavor profile.
1 cup heavy cream: This creates the luxurious, creamy sauce that coats the squash beautifully.
1/2 cup grated Parmesan cheese: Adds a sharp, salty element that perfectly complements the creaminess.
1 cup shredded Gruyère or Swiss cheese, divided: Gruyère offers a nutty, slightly sweet flavor, while Swiss provides a more mild, buttery taste. Both are excellent choices!
1/2 tsp dried thyme: A classic herb that pairs wonderfully with squash and adds an earthy aroma.
Salt and pepper, to taste: Seasoning is essential to bring all the flavors together. Don’t be shy!
1/4 cup bread crumbs (optional, for a crispy topping): Adds a delightful crunch to the top of the au gratin. Panko breadcrumbs are a great choice.
Fresh parsley, chopped (for garnish): Adds a pop of fresh, vibrant color and a touch of herby freshness.

Step-by-Step Instructions

Let’s get cooking! Follow these easy steps to create this amazing zucchini and yellow squash au gratin.

Preheat your oven to 375°F (190°C). This ensures the au gratin cooks evenly and gets beautifully browned on top.
Prepare the squash: Wash and thinly slice the zucchini and yellow squash. Aim for slices that are about 1/8 inch thick for even cooking. A mandoline slicer is helpful for consistent thickness, but a sharp knife works just fine too!
Sauté the aromatics: Heat the olive oil in a large skillet over medium heat. Add the diced onion and cook until softened, about 5 minutes. Add the minced garlic and cook for another minute, until fragrant. Be careful not to burn the garlic.
Combine the squash and sauce: Add the sliced zucchini and yellow squash to the skillet with the onions and garlic. Stir to coat with the olive oil. Pour in the heavy cream, and stir in the Parmesan cheese, thyme, salt, and pepper. Simmer for about 5-7 minutes, or until the squash is slightly tender but still retains some bite. Don’t overcook – you want the squash to remain vibrant and not mushy.
Assemble the au gratin: Pour the squash mixture into a greased 9×13 inch baking dish. Sprinkle half of the Gruyère (or Swiss) cheese evenly over the top. If using breadcrumbs, sprinkle them evenly over the cheese. Then, sprinkle the remaining Gruyère cheese on top.
Bake: Bake in the preheated oven for 20-25 minutes, or until the cheese is melted, bubbly, and golden brown, and the squash is tender. Keep an eye on it – ovens vary, so you might need to adjust the baking time slightly. If the top browns too quickly, loosely tent it with foil.
Garnish and serve: Remove the au gratin from the oven and let it rest for a few minutes before garnishing with fresh chopped parsley. Serve warm and enjoy!

Tip: For extra flavor, consider adding a pinch of nutmeg along with the thyme.

Tips for Success

Here are a few tips to ensure your zucchini and yellow squash au gratin turns out perfectly every time:

Don’t overcook the squash: Overcooked squash will become mushy. Aim for slightly tender-crisp squash.
Use a good quality cheese: The cheese is a key component of this dish, so splurge on a nice Gruyère or Swiss. The flavor difference is noticeable!
Don’t overcrowd the pan: If you overcrowd the pan while sautéing the squash, it will steam instead of sauté, resulting in less browning and a less flavorful dish. Work in batches if necessary.
Grease your baking dish well: This prevents the au gratin from sticking and makes it easier to serve.
Keep an eye on the oven: Ovens can vary, so monitor your au gratin closely to avoid burning. If the top browns too quickly, cover it loosely with foil.

Variations to Try

Feel free to experiment with different flavors and variations!

Add some heat: Incorporate a pinch of red pepper flakes for a spicy kick.
Use different herbs: Experiment with other herbs like oregano, basil, or rosemary.
Add other vegetables: Feel free to add other vegetables, such as mushrooms, bell peppers, or spinach.
Make it a vegetarian main course: Add some cooked quinoa or lentils to make this a hearty vegetarian main course.
Gluten-free option: Ensure your breadcrumbs are certified gluten-free if needed.

Storing and Reheating

Leftover zucchini and yellow squash au gratin can be stored in an airtight container in the refrigerator for up to 3 days. To reheat, simply microwave individual portions until heated through, or bake in a preheated oven at 350°F (175°C) for 10-15 minutes, until heated through and bubbly. Freezing is not recommended, as the texture may suffer.

Frequently Asked Questions

Here are some answers to frequently asked questions about this recipe:

Q: Can I substitute the Gruyère cheese? A: Yes! Swiss cheese, Fontina, or even a blend of cheddar and provolone would work well.
Q: How long does the au gratin keep in the refrigerator? A: It will keep for up to 3 days in an airtight container in the refrigerator.
Q: Can I use frozen squash? A: It’s best to use fresh squash for the best flavor and texture. Frozen squash can result in a watery au gratin.
Q: Can I make this ahead of time? A: You can assemble the au gratin ahead of time and bake it just before serving. Store the assembled dish, uncovered, in the refrigerator until ready to bake.
Q: What if my au gratin is browning too quickly? A: If the top is browning too quickly, loosely cover it with foil for the remainder of the baking time.

The Final Word

This creamy dreamy zucchini and yellow squash au gratin is a true crowd-pleaser. The perfect blend of textures and flavors, along with its vibrant colors, makes it a show-stopping side dish (or even a main course!). It’s easy to make, endlessly adaptable, and guaranteed to impress. So, give it a try and let me know what you think in the comments below! Don’t forget to rate the recipe and share your photos – I love seeing your culinary creations! Happy cooking!

Zucchini and Yellow Squash Au Gratin

A creamy, cheesy gratin featuring zucchini and yellow squash.

Print Recipe Pin Recipe

Prep Time 20

Cook Time 35

Servings 6 servings

Calories 350 kcal

Equipment

Baking dish 9×13 inch
Large skillet

Ingredients

Vegetables

2 medium zucchinis thinly sliced
2 medium yellow squashes thinly sliced
0.5 cup diced onion

Sauce and Topping

1 tbsp olive oil
2 cloves garlic minced
1 cup heavy cream
0.5 cup grated Parmesan cheese
1 cup shredded Gruyère or Swiss cheese divided
0.5 tsp dried thyme
0.25 cup bread crumbs optional, for a crispy topping
Salt and pepper to taste
Fresh parsley chopped, for garnish

Instructions

Preheat oven to 375°F (190°C).
In a large skillet, sauté the diced onion (ing_3) in olive oil (ing_4) until softened. Add minced garlic (ing_5) and cook for another minute.
Add the sliced zucchini (ing_1) and yellow squash (ing_2) to the skillet and cook until slightly tender.
Stir in heavy cream (ing_6), Parmesan cheese (ing_7), thyme (ing_9), salt (ing_11), and pepper (ing_11). Simmer for 5 minutes.
Pour the vegetable mixture into a greased 9×13 inch baking dish.
Sprinkle half of the Gruyère or Swiss cheese (ing_8) over the vegetables.
If using, top with bread crumbs (ing_10). Sprinkle the remaining cheese (ing_8) on top.
Bake for 25-30 minutes, or until golden brown and bubbly. Garnish with fresh parsley (ing_12) before serving.

Notes

This recipe can be easily adapted to your liking. Feel free to add other vegetables or cheeses.