Cheesy Spaghetti Squash Casserole

slice of spaghetti squash casserole cut with a fork on a plate.

Cheesy Spaghetti Squash Casserole

Course: Side Dish

Cuisine: American

Keyword: spaghetti squash casserole

Prep Time: 10

Cook Time: 45

Total Time: 55

Servings:

Calories: 141kcal

Author: Megan Gilmore

If you grew up eating classic hash brown casserole, you'll love this lower calorie alternative made with spaghetti squash. It's made with creamy Greek yogurt and sharp cheddar cheese, for a comforting side dish. When you start with cooked spaghetti squash, you can get this into the oven with less than 15 minutes of prep work.

Print Recipe Add to Collection

US Customary - Metric

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 information is for 1 of 6 servings (approximately 1 cup). This information is automatically calculated using ingredients from a generic online database, so it's just an estimate and not a guarantee.

Spaghetti Squash Note: This recipe assumes that you're working with the strands from a cooked 3-pound spaghetti squash. I weigh the squash using a food scale (affiliate link) to make sure it's at least 3 pounds, but I don't usually measure the cups that I get from the squash. So, as long as you're using approximately that weight, it doesn't matter how many cups you get from the squash. It should work for this recipe!

Update Note: This recipe was originally posted in 2013 and was updated in 2025. I originally used goat yogurt and goat cheddar cheese, but since those are not always easy to find ingredients, I updated it with Greek yogurt and sharp cheddar cheese. (Which tastes a little more classic, too.)

See the FAQ section for additional tips.

Nutrition