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If you’re not sure what to do with your next spaghetti squash, try making this cheesy spaghetti squash casserole. This healthy comfort food recipe reminds me of the classic hash brown casserole my mom used to make, only this version is made with spaghetti squash, for a lower-calorie twist.
All you need is a few simple ingredients, like Greek yogurt and cheddar cheese, to get started. It also helps if you’ve already baked your spaghetti squash ahead of time, but I’ll walk you through the best ways to cook it. (I’ve tested it in the oven, slow cooker, and Instant Pot.)
Once you taste this spaghetti squash recipe, I think you’ll want to repeat it all season long! It’s naturally gluten-free and makes an easy weeknight casserole idea. Add your favorite protein to make it a complete meal!
⭐⭐⭐⭐⭐ Featured Review
“Just made this. Used sharp white cheddar and sour cream as I didn’t have yogurt. Came out fantastic! Could’ve eaten the whole pan but husband beat me to it. Will definitely make again.” – Fey
Ingredients You’ll Need
- Spaghetti Squash. Cooked spaghetti squash has a surprisingly similar texture to hash browns, and blends seamlessly into this simple casserole, while being low in calories in carbohydrates.
- Greek Yogurt. My mom’s hash brown casserole called for sour cream, so I’ve opted for whole milk Greek yogurt, which has a similar tangy flavor and a lot more protein.
- Cheddar Cheese. I use sharp cheddar cheese for a flavor boost, without needing quite as much as traditional recipes call for.
- Onion and Garlic. Sauteed yellow onion helps add another layer of aromatic flavor, especially when paired with garlic. (Though garlic powder could be used in a pinch, if needed.)
How to Cook Spaghetti Squash
The most time-consuming part of this recipe is baking the spaghetti squash, but you can do this in advance to save time. Cooked spaghetti squash can be stored in an airtight container in the fridge for up to 5 days, so I usually make this casserole when I have some stored already.
To prepare the squash, cut it in half cross-wise (through the hollow center and not the ends) and scoop out the seeds. Then follow one of the cooking methods below. Click on the links below if you’d like to see step-by-step photos.
- In the Oven: Place the squash cut-side-down on a parchment lined pan and bake for 45 to 60 minutes at 400ºF, or until the shell is easily pierced with a fork.
- In the Slow Cooker: Add a 1/2 cup of water to the pot and arrange the squash halves cut-side-down. Cover with a lid and cook on high for at least 2 hours, or on low heat for 4 to 6 hours. When the shell is easily pierced with a fork, it’s ready to use.
- In the Instant Pot: Pour 1 cup of water into the stainless steel bowl of the Instant Pot. Add the trivet that comes with your machine, then arrange the squash halves cut-side down. Secure the lid and cook at high pressure for 7 minutes. When the cooking cycle is complete, quickly release the pressure. When the floating valve in the lid drops, it’s safe to open the lid.
Once the squash is cooked, you can use a fork to pull the spaghetti-like strands away from the shell. Transfer the cooked squash to an airtight container and store it in the fridge until you’re ready to use it.
I usually get approximately 4 cups of noodles from a 3-pound squash. (If it’s a little more or less than that, it’s okay, too.)
How to Make Spaghetti Squash Casserole
Step 1:
Preheat the oven to 400ºF and lightly grease an 8-inch square pan with cooking spray. Then, heat a skillet over medium high heat on the stove top for 1 to 2 minutes. This will make the surface less likely to stick.
Add a drizzle of olive oil to the pan and cook the onion for 5 minutes, stirring often, until it starts to soften. Then add the garlic and stir for one more minute.
Transfer the cooked onion and garlic to a large mixing bowl and add the Greek yogurt, a half teaspoon of fine salt, and a quarter teaspoon of ground black pepper. Stir well.
Step 2:
Add the cooked spaghetti squash to the bowl and approximately 3/4 cup of shredded cheddar cheese. (About 3 ounces). Season with another half teaspoon of salt, then stir well to combine.
Once it looks creamy and well mixed, transfer it to the prepared pan and sprinkle the remaining cheese on top. Bake at 400ºF for 35 to 40 minutes.
Step 3:
When the cheese looks lightly golden on top, remove the pan from the oven and let it cool for at least 10 minutes before serving. You can garnish the top with freshly chopped parsley or chives, if desired.
Use a spoon or spatula to scoop this casserole for serving. It makes a comforting side dish for practically any meal you have planned.
Cheesy Spaghetti Squash Casserole
Ingredients
- 4 cups cooked spaghetti squash (from a 3-pound squash)
- 1 tablespoon olive oil
- 1 yellow onion , chopped
- 1 garlic clove , minced
- 1 cup plain Greek yogurt
- fine sea salt and ground black pepper
- 4 ounces sharp cheddar cheese , shredded and divided
Instructions
- Preheat the oven to 400ºF and lightly grease an 8-inch square pan with cooking spray. Heat a skillet over medium high heat for 1 to 2 minutes. (This will make the surface naturally more non-stick.) Add a drizzle of olive oil to the pan and cook the onion until it starts to soften, about 5 minutes. Then add the garlic and stir for one more minute.
- Transfer the cooked onion and garlic to a large mixing bowl and add in the yogurt. Season with ½ teaspoon of salt and a ¼ teaspoon of ground black pepper, then stir well. Fold in the cooked spaghetti squash strands and ¾ cup of shredded cheese (about 3 ounces). Season with another ½ teaspoon of salt and stir to make sure the spaghetti squash is well seasoned.
- Transfer the mixture to the prepared pan and smooth the top with a spatula. Sprinkle the remaining ¼ cup (1 ounce) of shredded cheddar over the top, then bake at 400ºF until the top is lightly golden, about 35 minutes. Your kitchen will smell fragrant as it gets close to being done, so check on the casserole when it starts to smell good.
- Remove the casserole from the oven and let it cool for at least 10 minutes before serving. You can garnish with fresh parsley or chopped chives, if desired. Leftovers can be stored in an airtight container in the fridge for up to 5 days.
Notes
Nutrition
More Recipes to Try
- Healthier Breakfast Casserole (with spaghetti squash!)
- Roasted Sweet Potatoes
- Healthy Chicken Burgers
- Italian Spaghetti Squash Soup
If you try this recipe, please leave a comment and star rating below to let me know how you like it.
I pin a million recipes, yet rarely cook. And I never leave comments! However, this one caught my eye when it was compared to hash brown casserole! Yum. I’ve only cooked Spaghetti Squash twice. This recipe was extremely easy. Hardest thing was shredding the cheese since I usually buy cheese already shredded! It tastes fantastic. Thank you for sharing!
I have this in the oven now. I added shredded chicken breast and ricotta cheese and used sharp cheddar. It smells good. Thank you for your recipe
I made this, amazing, no leftovers!
I made this for dinner tonight. It was very good! I used the pressure cooker to cook the squash and it came together easily. Cheesy spaghetti squash was a satisfying substitute for cheesy potatoes. Thank you!
This was a super yummy side dish! I did use full fat sour cream and regular cheddar cheese (I’m on a low carb diet recommended from my endocrinologist to try to control my diabetes & drop weight) & this has to be one of the best side dishes I’ve had- it really feels like hash Brown casserole and tastes amazing. Thank you!
This is one of my favorite spaghetti squash recipes. I made it as a side dish with asparagus and blackened shrimp and it was a hit! My boyfriend went back for seconds just for the spaghetti squash! I used greek yogurt. I didn’t see a goat cheese that said cheddar, so I bought the goat cheese that was in block form to shred. Must try!
Really delicious! Even my kids who proclaim that they “hate squash” ate it!
Well I went to make this recipe and low and behold had no cheddar cheese , so I substituted with pecorino romano. Oh my Word this was soooooo delicious!!! I wish I could give it a ten rating!!! So indebted to you for my great dinners, :] Lyn :]
I had leftover spaghetti squash and was looking for a recipe to use it. This was perfect since I already had the squash baked. However I did not have plain Greek yogurt on hand so I used sour cream in a pinch and it worked great! The whole family loved it, I would definitely make this again and again! Thank you!
I’m so glad you enjoyed it!
I used your recipe as a springboard. I doubled it, and used regular shredded cheddar instead of goat cheddar, plus added frozen peas and two cans of tuna (drained). I also pulsed some Caesar croutons in my food processor and sprinkled the crumbs on top at the end, then popped it under the broiler until they browned.