Fresh summer squash is so tasty in this easy squash casserole! Tender squash in a creamy sauce with a crunchy parmesan and rosemary topping– a delicious twist on a classic dish.
The links below may be affiliate links, meaning I earn a small compensation at no extra cost to you. See my full disclosure policy here.
I have another summer garden recipe for you today! If you are harvesting a lot of yellow crookneck squash, or enjoying the abundance at the market, this delicious squash casserole is a great way to use up some of your squash.
Squash casserole was always a staple at my family’s holiday gatherings growing up. I wanted to make a similar version– but with a tasty twist. Using parmesan cheese and rosemary gives the casserole a new depth of flavor. It’s already met with rave reviews- by my family and our friends.
I also wanted to make sure that this dish could be made with simple, staple ingredients, and that it would also be something we didn’t have to reserve only for special occasions.
Rosemary & Parmesan Squash Casserole
The squash cooks until tender with some onions in a skillet. This is the longest step, but it’s pretty hands off. Just set them to sauté, and then stir occasionally as they soften and get extra tasty. You can even cook the casserole right in the skillet, or if you want, transfer it to a baking dish before topping it with crushed croutons, and more parmesan and rosemary.
The casserole doubles well too, and keeps warm if you need to make it ahead of time and serve it at a potluck or cookout. If you need to make it dairy-free or gluten-free, just make the necessary substitutions (dairy-free cheese, gluten-free croutons).
Rosemary & Parmesan Squash Casserole
- Prep Time: 10 minutes
- Cook Time: 40 minutes
- Total Time: 50 minutes
- Yield: 4-6 servings 1x
- Category: Side dish
- 1 tablespoon ghee
- 1 cup diced yellow onion
- 3 medium yellow squash, cut into 1/2” half moons
- 1 tsp kosher salt
- 1 1/2 tsp fresh chopped rosemary, divided
- 1 egg
- 1/2 cup mayonnaise
- 1/2 cup shredded cheddar cheese
- 3/4 cup shredded Parmesan cheese, divided
- 1 cup crushed croutons
- Melt the ghee in a 10″ skillet over medium heat. Add the diced onion and the squash, season with the salt and 1 teaspoon of rosemary. Stir to mix together the vegetables with the ghee and seasoning. Let the mixture cook, stirring a couple of times, for about 20-25 minutes, until the squash is fork tender. (You don’t want the squash to overcook and become mushy in the oven).
- Preheat the oven to 350 degrees after the squash mixture has been cooking for about 10 minutes.
- Put the croutons in a sandwich bag and smash with the bottom of a measuring cup or spoon. Stir together the egg, mayo, cheddar cheese, and a half cup of the parmesan cheese in a glass measuring cup. Remove the skillet from the heat, and stir in the egg mixture. Toss well to coat. You can cook the casserole in the skillet, or transfer to a baking dish. If cooking in a baking dish, transfer the squash mixture now.
- Top the squash casserole with the crushed croutons, then a 1/4 cup of shredded Parmesan, and finally with a half teaspoon of rosemary. Bake for 15 minutes in preheated oven.
- Serve immediately, or keep warm until ready to serve*.
*If you want to prep the casserole ahead of time, complete the first step and then keep the casserole in the fridge until you’re ready to bake. Wait to add the topping until just before baking.
Sharing is caring! Don’t forget to pin and share. Thank you!
Lisa chevy says
New family favorite to use up all of the squash growing in the garden! Subbed plain Greek yogurt for the mayo, ritz crackers for the croutons and dried rosemary for fresh .
Delicious! I make croutons from sourdough to use on top.
I usually use a combo of zucchini and yellow squash and substitute greek yogurt for the mayo. It is SO delicious! Crackers work for the crust, also. Recipe is perfection, as is, or with simple substitutions. Definitely a keeper!! <3
This was yummy! Used fresh basil, as it’s in season. Will freeze some zucchini for this to make in the winter.
so yummy! I don’t always follow it to a t, but pretty close most times. Love the crouton topping-genius idea!
Jennifer Maxwell says
Wow! This is an amazing dish! The flavors are so good together! Thank you for sharing yet another wonderful recipe!
Made this for a cookout this week, and it was a HUGE hit. So delicious! Thank you for sharing such a yummy recipe!