This baked squash au gratin casserole features layers of tender sliced zucchini and yellow squash smothered in a rich cream sauce with a golden brown crust of tangy cheese on top. It’s a must have Southern side dish at any summer supper that’s ready in just 30 minutes.
I may or may not have an … obsession.
A zucchini obsession.
It all started when I was inundated with bags and bags of free summer squash.
I had to do something with them.
I had to do something new too, since the sons wouldn’t stand for having one more slice of zucchini bread served to them.
Instead, they got these harmless little zucchini fritters.
Before them I really was only a casual zucchini user. Nothing much creative about it. Then I got really creative with this cheesy zucchini rice.
And then a couple of weeks ago I died and went to zucchini heaven with the glazed lemon zucchini bread.
But today, it’s official. We’ve revolutionized their use with this zucchini and squash au gratin.
Which is saying something since summer squash, especially zucchini, are pretty much one of the best, most versatile, veggies ever. Move on over potatoes, there’s a new star in town.
Take your abundant summer squash and transform it into a cheesy squash au gratin casserole the whole family will go nuts for!
Ingredients Needed
Summer cooking shouldn’t be hard or overly complicated, at least not in my kitchen- and this casserole fits the bill nicely!
To make it you’ll need:
- Squash – We use a 50/50 blend of zucchini and yellow squash, but you could use more or less of one depending on availability.
- Shallots – Two shallots, peeled & minced. If shallots are hard to find you can sub minced yellow onion.
- Garlic – Freshly minced cloves are best, but the jarred kind will work too- you may just need a little extra to enhance the flavor.
- Cream – Heavy whipping cream is the best kind to use, but in a pinch half & half will work.
- Cheese – Shredded mozzarella or provolone, depending on preference, and Parmesan cheese.
- Seasonings – This recipe uses a blend of salt & pepper, to taste, and dried oregano.
How To Make Squash Casserole (Au Gratin Style)
A simple ingredient list and simple instructions are all that stand between you and a delicious helping of this zucchini gratin with yellow squash. It’s a real Southern summer delicacy!
Start by thinly slicing your zucchini and squash into 1/8-1/4″ coins. Don’t chop or dice them. Thicker coins may require a longer cook time, but not by much.
Also try to pick medium sized squash, and avoid any that are overly large. Overly large squash are full of water and seeds, which don’t tend to be great for recipes where you want the meaty flesh.
Add the butter to a large skillet set over medium heat, and let it melt.
Once the butter’s hot, stir in the shallots & garlic. Sautee and stir often, just until the shallots have started to become translucent.
If using jarred minced garlic, wait to add it until the shallots have turned- then stir it in and allow it to cook for 30 seconds. This will remove any bitter taste, but any longer and it may burn and turn bitter.
Add the sliced squashes and cream to the skillet, and gently stir them to combine. Stir in the salt, pepper, oregano, and a 1/4 cup of Parmesan cheese.
Reduce the heat to medium low and allow this mixture to simmer, stirring often, for 8-10 minutes. Don’t let it come to a boil as the high heat can cause the cream to curdle.
Transfer the mixture to an 9×9″ baking dish, and sprinkle the shredded cheeses evenly out over top.
Bake the cheesy squash au gratin at 450 degrees Fahrenheit for 10-15 minutes, or until bubbly and the cheeses are melted and golden brown on top.
Remove the dish from the oven, and let it rest a full five minutes before scooping and serving.
Storing Leftovers
If you have extras, store them in an air tight container and refrigerate for up to 4-5 days.
To reheat, I recommend transferring this to a skillet on the stove top to bring the creaminess back out in the sauce.
Can You Make Squash Au Gratin Ahead Of Time?
Yes!
To make this zucchini gratin ahead of time, prepare it as instructed up until you transfer it to the baking dish. Let the mixture cool completely.
Cover and refrigerate, or freeze, until ready to use and then uncover and bake as instructed.
Can I Use Other Cheeses?
This squash au gratin casserole is very forgiving, and also super easy to customize to your liking.
Feel free to mix up the cheeses you sprinkle on top!
In addition to the provolone or mozzarella called for, we also love using sharp cheddar, colby jack, and even a savory smoked gouda.
TIPS & TRICKS
- To make clean up easier, lightly spray your baking dish with non stick cooking spray before using.
- Don’t overcook your squash, you want it to be soft but not mushy in the skillet. It will continue to soften during baking.
- You can make this in a cast iron skillet from start to finish (since it’s oven safe) and not have to worry about transferring or dirtying another dish. Just know those dishes tend to cook hotter and retain heat longer.
- For more flavor, use bacon grease in place of butter.
Other Summer Squash Recipes To Try
This cheesy squash au gratin with zucchini is to Summer, what the classic potato au gratin is to Winter. Seasonal vegetables cooked to tender perfection and bathed in rich, creamy deliciousness.
Make it and discover just how delicious squash can be!
Looking for other ways to use zucchini & yellow squash? Try one of these fan favorite recipes:
- Sautéed Summer Squash with Bacon & Onions
- Cheesy Chicken Pesto Squash Bake
- Stuffed Patty Pan Squash
- Crispy Garlic Parmesan Squash Chips
- Pimento Cheese Stuffed Squash
If you’ve tried these ZUCCHINI & SQUASH AU GRATIN CASSEROLE, or any other recipe on the site, let me know in the comment section how it turned out, we love hearing from our readers! You can also follow along with me on PINTEREST, FACEBOOK, and INSTAGRAM to see more amazing recipes and whatever else we’ve got going on!
Zucchini & Squash Au Gratin Casserole
Ingredients
- 2 tbsp butter
- 1 zucchini sliced
- 1 yellow squash sliced
- 2 shallots minced
- 1 tsp minced garlic
- 1/2 cup heavy cream or half and half
- Salt & Pepper to taste
- pinch dried oregano
- 1/4 cup Parmesan cheese
- 1 cup Shredded Cheese mozzarella or provolone works best
Instructions
- Melt butter in a large skillet over medium heat. When melted add in the shallots and garlic, and saute until they begin to turn clear.
- Next, add the zucchini, squash and cream. Give it a stir and then add the salt, pepper, and Parmesan.Cook the mixture 8 to 10 minutes over medium-medium low, stirring occasionally. You do not want it to boil, only lightly simmer.
- Pour the mixture into a baking dish and sprinkle the top with a little more Parmesan and evenly distribute the shredded cheese over top.
- Bake for 10 to 14 minutes at 450 degrees, or until the casserole is bubbly and golden brown on top.
Notes
- To make clean up easier, lightly spray your baking dish with non stick cooking spray before using.
- Don't overcook your squash, you want it to be soft but not mushy in the skillet. It will continue to soften during baking.
- You can make this in a cast iron skillet from start to finish (since it's oven safe) and not have to worry about transferring or dirtying another dish. Just know those dishes tend to cook hotter and retain heat longer.
- For more flavor, use bacon grease in place of butter.
Nutrition
recipe originally published August 6, 2014
Traditionally Modern Food says
Looks delicious:-)
Chitra Jagadish says
Wow yummy. …
Audrey says
Mmmm with cheese! My favorite way of eating zucchini!
Kaila511 says
I love zucchini and squash, glad to hear they are competing with potatoes! Have a wonderful weekend. 🙂
Miz Helen says
We will just love this dish! Thanks so much for sharing with Full Plate Thursday and have a great weekend!
Come Back Soon!
Miz Helen
saucygander says
The gratin sounds heavenly!! Saving this recipe! And thank you for sharing this with Fiesta Friday, as it sounds like a few people are facing the annual squash/zucchini glut. Enjoy the fiesta party!
Miz Helen says
Congratulations!
Your Recipe is featured on Full Plate Thursday this week. Hope you enjoy your weekend and your new Red Plate!
Come Back Soon,
Miz Helen