Creamy and comforting, this Spaghetti Squash Casserole makes a perfect keto side dish. Easy and cheesy, with tons of flavor, it turns your dinner into a hearty meal.
I had an absolute bumper crop of spaghetti squash from my garden this year. We grew a variety called stripetti with pretty green stripes, and we weren’t expecting that much out of it. It far exceeded our expectations.
And now we have so many, we need to find ways to use it up. So I am dreaming up as many spaghetti squash recipes as I can! And this creamy, cheesy Spaghetti Squash Casserole is one such recipe.
Oh boy, is it ever good. So hearty and flavorful, this might be my new go-to side dish for fall. At least until I work through all those squash. And with only 5.6g net carbs per serving, it fits the keto diet perfectly.
I may have eaten the leftovers for breakfast too. It goes perfectly with a fried egg and a few slices of bacon. Just saying!
Make sure to try my Twice Baked Spaghetti Squash too. It’s another of my favorites!
Ingredients you need
- Spaghetti squash: You will need a medium-size spaghetti squash for this recipe, which should be about 3 pounds in weight when whole. It will yield about 4 cups cooked squash.
- Sour cream: Sour cream gives the casserole a thick and creamy consistency.
- Garlic: I recommend using fresh garlic for the best flavor. You can use pre-minced, jarred garlic instead. If all you have is garlic powder, try using 1 teaspoon.
- Italian seasoning: This dried seasoning blend pairs perfectly with the squash and cheese.
- Shredded cheese: I used a mild cheddar for the filling and mozzarella for the top of the casserole, plus some Parmesan to play up the Italian flavor. But you can use other cheese as well. Fontina or gruyere would be lovely.
- Eggs: The eggs help bind the stringy squash together and give it a more coherent consistency.
- Basil: Fresh basil adds both color and flavor.
- Kitchen staples: Butter, salt, pepper, red pepper flakes
Step by step directions
1. Pre-cook the squash: Cut the spaghetti squash in half, crosswise, and scoop out the seeds. Place cut-side down on the prepared baking sheet and bake at 375ºF for 45 to 60 minute, or until the squash can be squeezed.
2. Scoop out the flesh: Remove and let cool for a few minutes, then scoop the flesh of the squash into a large bowl. Add the butter and let melt.
3. Mix the filling: Add the sour cream, garlic, Italian seasoning, salt, pepper, and red pepper flakes, and stir to combine. Then stir in the eggs, cheddar, and half of the Parmesan until well combined.
4. Sprinkle with cheese and bake: Spread in the prepared baking pan and top with the mozzarella and the remaining Parmesan. Bake at 350ºF for 30 to 35 minutes, until bubbly and browned.
Expert tips
I like to use a large heavy duty spoon for scooping out the seeds of the spaghetti squash. The flesh is quite tough when raw, so a flimsy spoon can easily bend under the pressure.
If your squash is larger than 3 pounds and yields more than 4 cups of cooked flesh, just save the rest for another use. You can refrigerate it for 4 or 5 days, or freeze it for up to 2 months.
Make it a meal!
Turn this spaghetti squash casserole from a side dish into a full meal. Try adding some cooked Italian sausage, ground beef, or cubed chicken to the filling. Then top with cheese and bake as directed.
Frequently Asked Questions
Spaghetti squash is a good option for keto and low carb diets, but some moderation is required. 1 cup of cooked spaghetti squash has 10g of carbs and 2.2g of fiber, so it’s a little higher in carbs than summer squash like zucchini. So it’s good to be mindful of how much you consume in one sitting.
The rind of spaghetti squash is very tough and hard to cut through. Make sure you use a very large, sharp knife and cut on a stable surface. Once you get through the first part of the rind, you will find it easier to cut through the rest. Cutting the squash in half crosswise is also easier than cutting lengthwise, as it’s a shorter distance.
This creamy spaghetti squash casserole has only 6.7g of carbs per serving and 1.1g of fiber. That amounts to 5.6g net carbs per serving.
Make Ahead and Storage Tips
If you want to get a jump on meal prep, this Spaghetti Squash Casserole is an ideal make-ahead side dish. You can roast the squash several days in advance, and just keep it in the fridge until you’re ready to assemble.
Or you can bake the full casserole and store it in the fridge for up 5 days, or the the freezer for up to two months. Make sure to wrap it up tightly to avoid freezer burn. Let it come to room temperature before warming it through in the oven.
More side dishes you might like
Spaghetti Squash Casserole Recipe
Ingredients
- 1 medium spaghetti squash, about 3 pounds
- 2 tbsp butter
- 1/2 cup (115 g) sour cream
- 4 cloves garlic, minced
- 1 tsp Italian seasoning
- 3/4 teaspoon (0.75 teaspoon) salt
- 1/2 tsp (0.5 tsp) pepper
- 1/4 tsp (0.25 tsp) red pepper flakes
- 4 ounces (113.4 g) white cheddar, grated
- 2 large eggs
- 1 ounce (28.35 g) freshly grated Parmesan, divided
- 2 tbsp chopped fresh basil
- 4 ounces (113.4 g) mozzarella, grated
Instructions
- Preheat the oven to 375ºF and line a baking sheet with parchment paper.
- Cut the spaghetti squash in half, crosswise, and scoop out the seeds. Place cut-side down on the prepared baking sheet and bake 45 to 60 minute, or until the squash can be squeezed.
- Remove and let cool for a few minutes, then scoop the flesh of the squash into a large bowl. Add the butter and let melt.
- Reduce the oven temperature to 350ºF. Lightly grease a 2 quart casserole dish.
- Add the sour cream, garlic, Italian seasoning, salt, pepper, and red pepper flakes, and stir to combine. Then stir in the eggs, cheddar, and half of the Parmesan until well combined.
- Spread in the prepared baking pan and top with the mozzarella and the remaining Parmesan. Bake 30 to 35 minutes, until bubbly and browned.
- Let cool a few minutes before serving. Sprinkle with additional chopped basil, if desired.
Notes
Storage Instructions:
Store the casserole in the fridge for up 5 days, or the the freezer for up to two months. Make sure to wrap it up tightly to avoid freezer burn. Let it come to room temperature before warming it through in the oven.Nutrition
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once you cook the spaghetti squash for 45 to 60 mins and then you mix all the other ingredients in a separate bowl (sour cream, garlic, Italian seasoning, etc). then you move the spaghetti squash into the 2 quart dish and place all the other ingredients on top and bake some more? just trying to clarify if we are cooking the spaghetti squash two times in this case? thanks!
Yes… you have to soften it properly to even get it out of the shells! 🙂
Hi Carolyn, All Day I Dream About Food. I bought my spaghetti squash yesterday to make this dish. Since it will be for just me, I purchased a 1.88lb squash. I will make this tomorrow and have a meatloaf with it. I am looking forward to having this delicious sounding dish. My only change is using yellow cheddar instead of white, since my supermarket didn’t have white cheddar. I have provolone, but provolone has a bit of a smoky flavor that I don’t want in this dish. I am so eager to make this dish I had to force myself not to keep commenting on your FB page – but I will after I make the dish. Thank you for everything you do to keep keto fun!
This casserole was absolutely delicious! I served it for super bowl dinner to all the vegetarians at the table. I used Impossible Beef to add bulk. While I usually don’t use that because it is so processed, it was perfect in this recipe.
I took this to a church potluck (double recipe). Everyone loved it! Thank you Carolyn!
Wonderful!
I really enjoyed this dish. I don’t have a lot of experience cooking with spaghetti squash and wasn’t sure what to expect. I can say it has a good flavor and the texture reminded me of shredded potatoes. I will make this again. I can see it being good with chicken for a dinner or maybe even eggs and bacon? Either way, thank you for this recipe!
I made this for dinner tonight and we enjoyed it. I managed to find an exactly 3-pound squash, and it cooked perfectly in 45 minutes. I used goat gouda for my cheese in place of cheddar. The one thing I would do differently is use a bit less garlic and saute it first because it does not cook much during the baking process. I was surprised to find the casserole very liquidy when I served it, and I’m not sure where that came from, given that I followed the recipe amounts (I did add two cups of chopped cooked chicken, but that shouldn’t have caused the problem). Any ideas on how to get it less liquidy? Let it sit more than 5 minutes after removing from the oven? I definitely want to make this casserole again – it tastes good and I have fun playing with spagnetti squash.
Chicken releases moisture too! You could try adding 1/2 tsp of glucomannan to the mixture before baking.
Thanks for the suggestion, Carolyn. I’ll definitely try it.
Made this last night and a major smash hit! My husband brought home a squash the size of my head, which measured to approximately 6 cups of squash. So I adapted the recipe accordingly (three eggs instead of two, etc) and used a 9 X 13 pan instead. Non-Keto eaters came back for more. Just had leftovers and was impressed all over again. Creamy, cheesy, garlicky, and surprisingly sweet. An excellent find!
So delicious! Made it last night paired with leg of lamb, and everyone loved it. One thing I did differently – the cheese wasn’t browned on top at the 30 minute mark, so I increased the oven temp to 400 for 15 mins. That was enough to form a nice cheesy crust on top. This dish will be my replacement for cheesy pizza (which I love and miss). I ate it for lunch sprinkled with red pepper flakes and salt, and it was perfect!
This is SO good! Yummy, cheesy…. I will definitely be making this again often!!
Well this is going into regular rotation as a side dish. Incredibly tasty and very very versatile. I sautéed mushrooms and added cut up chicken thighs but the possibilities are endless. Sautee some spinach. Add any kind of veggie, really. I find side dishes to be hardest to come up with, and this will pair well with so many different meats. Thank you Carolyn for a superb recipe (yet again).
I always cook my spaghetti squash in the instant pot. Cut the squash in half width-wise instead of lengthwise & remove the seeds. 8 minutes & it’s done!
The best spaghetti squash recipe ever! We had a bumper crop, too, so there’s been a brisk competition for the title. I roasted a head of garlic along with the squash, mashed it with a bit of oil and added it into the mix. Oh, and a 10 minute trip through the microwave first will help make the orneryest old squash easier to cut in half. Be sure to stab it several times first so it doesn’t explode in the microwave.
This is delicious! I didn’t have the basil but didn’t miss it. Otherwise, I made it exactly as directed. Enjoyed by my non-keto guy as well. Make it!
Wow! This is sooo good. Generally we don’t care for spaghetti squash, but this was excellent. It was savory and had a consistency similar to mashed potatoes. My teen and I couldn’t get enough. Thank you for such a treat!
So great to hear!
Loved the Spaghetti Squash Casserole!
I’ve made a similar recipe that I got from a George Stella cookbook called mock hash brown casserole. You can use the squash or grated cauliflower. It also uses onion, cheddar cheese, sour cream, cream cheese, and bacon bits.
Also, I put a couple slits in my squash to release steam and microwave it. You then cut in half and remove seeds. It’s so much easier to cut then. Seeds come out easy too. Thanks for all your recipes!
Question! Do you still roast the squash in the over after you microwave it? Or is it done enough in the microwave?
Just saw this and made it for dinner. Added some ground sausage per your suggestion and made it a main dish. Hubby and I loved it! Thanks for another amazing recipe.
On a side note, I’ve given up attempting to grow spaghetti squash. The squirrels always seem to nibble on each and every squash that gets close to being ripe. Not worth the frustration. I don’t mind sharing a few with our local wildlife, but I need some uneaten for my efforts and care.
Interesting, a cross between a spaghetti squash and a delicata squash.
It is! Exactly… except the flesh is spaghetti squash. Pretty, though! And boy, did they ever produce for us.
This looks delicious. I love spaghetti squash. A tip for cutting. I microwave mine for about 5 minutes and then cut open. Make sure you poke it a few times with a fork. This method saves a trip to the ER. Lol.
If my knives were dull, this would be a great tip! 🙂
This recipe sounds wonderful! I would definitely make it a whole meal, because I don’t use side dishes very often. One tip, for those who don’t have experience with spaghetti squash: don’t overcook it – in my experience the squash becomes bitter when it is overcooked. If you have a small squash, definitely check it after 45 minutes.
Thanks! That’s why I give a range of time. Once it’s squeezable from the outside, it’s done.
Hi Carolyn, Love your blog. This spaghetti squash recipe sounds great. Unfortunately for me, my husband doesn’t like sour cream. What would this recipe be like without the sour cream?
Don’t tell him there’s sour cream in it and he’ll never know. He’ll think it’s cream????