This cheesy spaghetti squash casserole is made with sour cream and cheddar. It's great as a side dish but is substantial and filling enough to serve as a meatless main course.
The leftovers are excellent, and you can quickly reheat them in the microwave.
This casserole is cheesy, delicious, and easy to make. I started making it whenever I had leftover baked spaghetti squash or microwave spaghetti squash.
But it's so good, I now make it whenever I get the chance. You can make it as written or add mix-ins and turn it into a complete meal. The possibilities are endless!
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Ingredients
You'll only need a few simple ingredients to make this casserole. The exact measurements are included in the recipe card below. Here's an overview of what you'll need:
- Spaghetti squash: I use a 3-pound squash in this recipe.
- Egg: I use large eggs in most of my recipes, this one included.
- Sour cream: Please use full-fat sour cream.
- Minced garlic: Mince it yourself, or use the stuff that comes in a jar.
- To season: Kosher salt, black pepper, and dried thyme.
- Shredded sharp cheddar: Extra-sharp cheddar is even better. It's more flavorful.
Variations
- Add more veggies, such as ½ cup of sauteed spinach (drain it well), ½ cup of sauteed mushrooms, ¼ cup of sauteed onions, or ¼ cup of chopped green onions.
- Add a cup of cooked and shredded grilled chicken breast (plus an extra ¼ cup of sour cream) and turn this casserole into a complete meal.
- I sometimes add ½ cup of bacon bits to the mixture.
- You can use different cheeses. Provolone, gruyere, and gouda are excellent options.
- Use softened cream cheese instead of sour cream.
- You can use dried oregano instead of thyme. Both work equally well.
- Substitute a teaspoon of garlic powder for the minced garlic.
Like all casserole recipes, this one is flexible and forgiving. So go ahead and experiment with your own additions!
Instructions
Scroll down to the recipe card for detailed instructions. Here are the basic steps for making this recipe:
Your first step is to cook the squash. I usually microwave it, but you can also bake it in the oven. Scoop out the pulp and seeds, and rake a fork back and forth to remove strands of the flesh into a bowl.
Whisk an egg, sour cream, and spices in a bowl. Add the squash strands and shredded cheese and mix until uniform.
Transfer the mixture to a greased baking dish and bake it until browned, for about 40 minutes, in a 400°F oven.
Let the casserole rest, then cut it into four squares and serve.
Expert Tips
Cutting or Scooping the Casserole
Thanks to the addition of egg, this casserole is sturdy enough to cut into squares, as shown in the photo below. If you'd like to omit the egg, increase the sour cream to ¾ cup and use a large spoon to scoop the casserole onto plates.
Here is the casserole served on a plate after it was cut into squares:
You Can Double This Recipe
When I serve this recipe to a larger group, I double this recipe and bake it in a 3.5-quart baking dish (such as a 9 X 13 baking dish) or Dutch oven, as shown in the photo below:
If you double the recipe, you can microwave the two squashes at the same time. Microwave them for six minutes on the first side, six more minutes on the second, and then flip them again and microwave for six more minutes or until they are soft:
Recipe FAQs
There's no need to add flour. The egg acts as a binder, and the sour cream adds substance and creaminess. The casserole's texture is excellent without any added starch.
Yes. You can bake it in the oven or microwave it. I prefer microwaving because it's easier and faster.
I don't recommend that. I tried it, and it wasn't as good.
Serving Suggestions
This casserole makes an excellent side dish but is also substantial and filling enough to serve as a meatless main dish.
I usually serve it as a side dish. And since I bake it in a 400°F oven, I like to serve it with a main dish that I can cook in the same oven, such as:
Storing Leftovers
You can keep the leftovers in the fridge, in a sealed container, for up to four days. I like to keep them in a glass food storage container, as shown in the image below:
You can also freeze this casserole. Allow it to cool completely, then wrap it in a plastic wrap layer and then foil. It can be frozen for up to three months.
Reheat the leftovers gently in the microwave at 50% power. Here's a recent dinner plate I made with reheated spaghetti squash casserole, oven-baked ribs, and pickled okra:
More Casserole Recipes
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Recipe Card
Spaghetti Squash Casserole
Ingredients
- Olive oil cooking spray
- 1 (3 pounds) raw spaghetti squash - or 2 ½ cups (450 grams) cooked spaghetti squash
- 1 large egg
- ½ cup sour cream
- 1 teaspoon Diamond Crystal kosher salt - or ½ teaspoon of any other salt
- ¼ teaspoon black pepper
- ½ teaspoon dried thyme
- 1 tablespoon fresh garlic - minced
- 1 cup cheddar cheese - sharp, shredded
Instructions
- Preheat the oven to 400°F. Lightly spray a 1.5-quart baking dish with olive oil cooking spray.
Microwave the squash:
- Pierce the spaghetti squash in a few spots with a sharp knife. Microwave it for 6 minutes; turn to the other side and microwave for 6 more minutes until soft to the touch. Let it stand for 5 minutes to finish cooking.
- Using a sharp knife, cut the spaghetti squash in half lengthwise. Allow it to cool for 5 minutes until it's easier to handle. Scoop out the pulp and seeds from the center, then rake a fork back and forth to remove strands of the flesh onto a bowl. Set aside.
Prepare the casserole:
- In a large bowl, lightly whisk the egg. Add the sour cream, kosher salt, black pepper, dried thyme, and minced garlic. Whisk until smooth.
- Mix in the cooked spaghetti squash and the shredded cheese.
- Transfer the mixture to the prepared baking dish. Bake until browned, about 40 minutes (it will smell wonderful!).
- Allow the casserole to cool for 10 minutes, then scoop it onto plates or carefully cut it into squares and serve.
Video
Notes
- You can add more veggies, such as ½ cup of sauteed spinach (drain it well), ½ cup of sauteed mushrooms, ¼ cup of sauteed onions, or ¼ cup of chopped green onions.
- Or add a cup of cooked and shredded grilled chicken breast plus an extra ¼ cup of sour cream and turn this casserole into a complete meal.
- Thanks to the addition of egg, this casserole is sturdy enough to cut into squares. If you'd like to omit the egg, increase the sour cream to ¾ cup and use a large spoon to scoop the casserole onto plates.
- You can keep the leftovers in the fridge, in a sealed container, for up to 4 days. Reheat them gently in the microwave at 50% power. You can also freeze this casserole. Allow it to cool completely, then wrap it in a plastic wrap layer and then foil. It can be frozen for up to three months.
- You can double this recipe and bake the casserole in a 3.5-quart baking dish, such as the Dutch oven shown in the photos on this page, or a 9 X 13-inch baking dish.Â
Nutrition per Serving
Disclaimers
Cup measurements refer to the standard American cup, which is 240 milliliters. Most of my recipes are low-carb (or keto) and gluten-free, but some are not. Please verify that a recipe fits your needs before using it. Recommended and linked products are not guaranteed to be gluten-free. Nutrition info is approximate, and the carb count excludes non-nutritive sweeteners. Nutrition info may contain errors, so please verify it independently. Recipes may contain errors, so please use your common sense when following them. Please read these Terms of Use carefully before using any of my recipes.
Vered DeLeeuw, LL.M., CNC, has been following a low-carb real-food diet and blogging about it since 2011. She's a Certified Nutrition Coach (NASM-CNC), has taken courses at the Harvard School of Public Health, and has earned a Nutrition and Healthy Living Certificate from Cornell University. Her work has appeared in several major media outlets, including Healthline, HuffPost, Today, Women's Health, Shape, and Country Living. 
Crosby
My sister made this while I was visiting and I was blown away! Making it today and I am adding bacon bits and shredded chicken seasoned and marinated for days with avocado oil, old bay, s&p, Mrs.Dash original, a little cumin and coriander. I will probably eat every bit of it .
Vered DeLeeuw
Yum! Loving these additions. Save me some! 🙂
Sarah F.
I just made this for lunch and it is so good! The hardest part of course is scraping out the spaghetti squash but other than that this recipe is so simple. my fiancé and I liked it a lot and I feel like it would be super easy to modify and add other things to if you wanted.
Vered DeLeeuw
I'm so glad you and your fiancé enjoyed this casserole, Sarah! Thank you for taking the time to write a comment.
Karen P
I think this tastes like cheesy garlic bread without the carbs. I left out the thyme but probably added more garlic than the recipe called for. Delicious!
Vered DeLeeuw
I'm so glad you liked this casserole, Karen! Thank you for leaving a comment.