If you love zucchini recipes, you’re going to adore this one. This is the best cheesy squash casserole recipe and the only one you’ll ever need! Yellow squash, fresh zucchini, cheese and more combine to make an amazingly easy and mouthwatering casserole!

When I was a teenager, I spent some time with an evangelist friend of my father’s and wife Debbie. One of my favorite recipes that Debbie cooked while I was there was a simple squash casserole recipe.
Since I was only a teenager, I did not think to ask her what the recipe was, but it was my first introduction to how amazingly yummy squash and zucchini could be. I looked for over twenty years for the recipe. No seriously. Twenty years. She was unable to remember it and I was unsure what was even in it. I just remember loving it.
So I was more than thrilled when I came across THIS recipe from Paula Deen for her cheesy squash casserole.
And then I was very, very, very sad because frankly that recipe is horribly bland and kind of tasteless.
How to Make a Cheesy Squash and Zucchini Casserole
It’s nothing against Paula Deen. She does her own thang and I adore most of the other recipes of hers that I’ve tried. I just found this particular one…lacking.
It took three total tries to get it just right but oh my soul, the final result is something just shy of amazing! It’s decadent, rich and yes, full of ooey, gooey, cheese! It’s been one of my favorite zucchini recipes since I got it right!
Can you freeze cheesy squash casserole with zucchini?
Since Steve is an OTR trucker and I cook for him, I was curious if this cheesy squash and zucchini casserole recipe would freeze well. I was not exactly hopeful though since it does have sour cream in it.
I was wrong. It freezes and reheats very well provided you know how to reheat it to keep it together. Don’t worry. I’m gonna tell you how to do just that.
It is a bit of a process but is totally worth it.

How to Freeze Cheesy Squash Casserole
To freeze this cheesy zucchini casserole, make it as directed below then allow it to fully cool. Scoop it into a food safe storage container and freeze it.
When you’re ready to reheat it, reheat it from frozen. Do not allow it to thaw as it will become watery if you do. Microwave it in 60-second increments making sure to stir it well in between each round. Depending on the amount you are reheating, this could take a while.
Like I said, it is a process so it works best for single serving sizes rather than reheating the entire thing. But, the freezing/thawing process is verified by the hubby so there you go.
What to Serve with the Best Cheesy Squash Casserole
This squash casserole goes well with so many dishes and even can stand on it’s own as a meal. We serve it with steak, chicken and even meat loaf. It pairs especially well with steak and a a salad.
To make it it’s own meal, mix in cooked shredded chicken – in large shreds – before you bake.

This makes one 9×13 baking dish.
You Will Need:
- Kitchen Knife or Mandolin Slicer like THIS
- 3 Yellow Squash, sliced thinly
- 3 Zucchini, sliced thinly
- 4-8 oz. mushrooms
- 2-3 Tbsp. Minced Garlic
- 4 Tbsp. Salted Butter
- 1 Small White Onion, diced
- 1 tsp Italian seasoning
- 1 tsp black pepper
- 8 oz. sour cream
- 4 oz. parmesan cheese, shredded
- 8 oz. Colby-jack cheese, shredded

A Quick Word About Ingredients
I have been blogging recipes long enough that I can already “hear” a few of the questions some will have so please let me try to answer them now. Please don’t think I’m being snarky. I simply want your own casserole to turn out amazing from the very first time you make it!
Yes, you can use unsalted butter. It will not affect the taste all that much. But please do use real butter and not margarine.
Yes, you may use canned mushrooms if you do not have fresh. Another great option is to use dehydrated mushrooms if you have any on hand. That is actually what I used when I was taking the photos for this post. If you have never dehydrated mushrooms before, I have a step by step tutorial on how to dehydrate mushrooms right HERE.
Yes, use real parmesan cheese for this. It comes in wedges or little bowls in the refrigerated section. Do not use the Kraft shaker stuff please. That isn’t real parmesan. It will affect the taste of your casserole. I’d rather see you leave out the parmesan than use the shaker stuff.
Yes, you can use cheddar instead of Colby-jack. It will change the taste a bit but not enough to really matter. Again, freshly shredded is best.

Cheesy Squash Casserole
Equipment
- Sharp Kitchen Knife or Mandolin Slicer
- Large Fry Pan
- 9×13 Baking Dish or large cast iron skillet
Ingredients
- 3 med. yellow squash sliced thinly
- 3 med. zucchini sliced thinly
- 4-8 oz. white button mushrooms washed and sliced
- 2-3 Tbsp. minced garlic
- 1 small/med. white onion diced
- 4 Tbsp. salted butter
- 8 oz. Sour Cream
- 4 oz. parmesan cheese shredded
- 8 oz. Colby jack cheese shredded and divided
- 1 tsp. black pepper
- 1-2 tsp. Italian seasoning optional
Instructions
- Preheat oven to 350° F. Wash and slice squash and zucchini thinly and dice onion. Add butter to large fry pan and sauté onion, garlic and mushrooms until soft and fragrant.
- Add zucchini and squash to pan and fry until soft stirring often. In a separate bowl, combine all ingredients except cheeses. Add squash mixture and stir until fully incorporated.
- Add all parmesan cheese and 1/2 Colby-Jack cheese to mixing bowl. Stir gently until incorporated.
- Pour mixture into baking dish or cast iron skillet, sprinkle Italian seasoning evenly over the top (if using) and cover with foil. Bake at 350° F for 15-20 minutes or until cheese is melted fully. Remove foil and broil on low for 3 minutes to brown cheese slightly making sure it does not burn. Remove from oven and allow it to rest for 8-10 minutes.