Spaghetti Squash Casserole with mushrooms, creamy goat cheese sauce, and crispy Parmesan topping. Enjoy this low-carb baked spaghetti squash casserole as a side dish or the main event.
Why You’ll Love this Spaghetti Squash Casserole
If you mostly only enjoy spaghetti squash as a side dish, this casserole is the perfect way to explore its potential as a main course. The spaghetti squash’s neutral flavor makes it easy to blend with a wide range of flavors. Plus, it’s a low-carb source of fiber, as well as vitamins A and C.
The casserole filling is a savory mix of shallots, mushrooms, and garlic cooked in a creamy goat cheese sauce. Right before baking, the casserole gets topped with a crispy panko-Parmesan topping, which elevates the whole dish. You can even get a head start by roasting the spaghetti squash up to three days in advance.
Serve this baked spaghetti squash casserole as the main event, or pair it with your favorite protein. It compliments chicken, red meat (or meatless grounds), or tofu like a dream.
Recipe Ingredients and Substitutions:
- Spaghetti Squash: You need roughly 6 cups of the spaghetti-like strands from the squash flesh. This amounts to 2 small-medium sized spaghetti squashes.
- Mushrooms: For savory, umami flavor and meaty texture, baby bella (or cremini) mushrooms do the trick. You can also shiitake or sliced portobello mushrooms, if you prefer.
- Aromatics: A mix of shallots, garlic, and fresh thyme create earthy, aromatic flavor for this casserole. Alternatively, you can use chopped yellow onion here.
- Spinach: For a pop of color and extra dose of nutrients, fresh baby spinach ups the veggie ante here. You need roughly two handfuls of fresh spinach, however you can also kale or chard, if you prefer.
- Cheese: To create a creamy, delightfully tangy sauce, this recipe calls for a whole 4-oz. log of goat cheese. It’s helpful to let the cheese come close to room temperature before mixing it in the sauce. This will ensure it melts and melds effortlessly into the sauce.
- Broth + Milk: A mix of vegetable (or chicken) broth and milk are the other necessary contenders for the cream sauce. I use unsweetened almond or cashew milk, however you can also use 2% dairy or whole-milk.
- Topping: The crispy Parmesan panko topping is the crown jewel of this casserole. It’s made with 3 simple ingredients: panko breadcrumbs, grated Parmesan cheese, and just a pat of butter.
Step 1: Bake Spaghetti Squash
Step 2: Cook Mushrooms and Aromatics
Step 3: Whisk in the Flour, Broth, and Milk
Step 4: Add Goat Cheese and Spaghetti Squash
Next, add the goat cheese and cook for 2 to 3 more minutes, stirring often, until the goat cheese melts and melds into the mixture. Once the sauce is made, add the spaghetti squash strands. Use a pair of tongs to toss the squash with the sauce until everything is well-combined.
Grease an 8×8 or 9×9 inch baking pan with non-stick cooking spray. Transfer the spaghetti squash casserole filling to the baking dish and set aside.
Step 5: Make Panko-Parmesan Topping
Step 6: Bake Spaghetti Squash Casserole
Make Ahead and Storage Tips
- To Make Ahead. Spaghetti squash can be roasted, shredded, and stored in an airtight container for up to 3 days ahead. This will save you up to an hour when you’re ready to prepare the casserole.
- To Store. Store leftovers in the refrigerator for up to 4 days.
- To Reheat. Either reheat individual portions in the microwave, or place the whole pan back in the oven at 350ºF until warmed through.
More Delicious Spaghetti Squash Recipes:
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Spaghetti Squash Casserole with Mushrooms and Goat Cheese
- Large skillet
- 8x8 or 9x9 inch baking dish
- 6 cups spaghetti squash strands from 2 small (2 lb.) squashes or 1 large (4 lb.) squash
- 2 Tbsp. olive oil
- 8 oz. sliced cremini (baby bella) mushrooms
- 1/2 cup chopped shallots
- 1 Tbsp. minced fresh garlic
- 1/4 tsp. red pepper flakes
- 2 cups fresh baby spinach
- 3 Tbsp. all-purpose flour
- 1 cup chicken or vegetable broth
- 1 cup milk of choice (I use unsweetened cashew or almond milk)
- 1/2 tsp. kosher salt
- 1/4 tsp. black pepper
- 1 Tbsp. fresh thyme leaves
- 1 (4-oz.) log goat cheese, softened
- 1 Tbsp. butter
- 1/2 cup plain Panko breadcrumbs
- 1/2 cup grated Parmesan cheese
- Preheat oven to 375ºF. Slice the squash in half lengthwise and scoop out the seeds. Rub oil onto the flesh, or lightly coat with non-stick cooking spray. Place squash halves, flesh side-down, on a baking sheet lined with foil.For two small squashes, bake for 35 to 40 minutes. For one large squash, bake for 45 to 50 minutes, or until the flesh of the squash is easily pierced with a fork.When cool enough to handle, pull the squash strings out of the squash's center with a fork and transfer to a large bowl.
- In a large skillet, heat 2 Tbsp. oil over medium-high heat. Once hot, add the mushrooms and shallots; cook 6 to 7 minutes, or until soft. Add garlic, red pepper flakes, and spinach; cook 1 to 2 minutes, stirring often, until the spinach wilts down.
- Whisk in the flour and cook for 2 FULL minutes. Slowly stream in the broth and milk, whisking constantly, until the liquids are fully combined. Simmer mixture for 5 to 6 minutes, until thickened. Season with salt, pepper, and fresh thyme.
- Add the goat cheese and cook for 2 to 3 more minutes, stirring often, until the goat cheese melts and melds into the mixture. Once the sauce is smooth, add the spaghetti squash strands. Use a pair of tongs to toss squash with the sauce until everything is well-combined.
- Grease an 8x8 or 9x9 inch baking pan with non-stick cooking spray or butter. Transfer the spaghetti squash casserole filling to the baking dish and set aside.
- Wipe the skillet clean and return to medium-high heat. Add 1 Tbsp. butter. Once melted, add the Panko breadcrumbs and lightly toast for 3 to 5 minutes, or until slightly golden. (Watch closely to avoid burning.) Transfer breadcrumbs to a bowl and toss with Parmesan cheese. Sprinkle the Panko-Parmesan mixture over the spaghetti squash casserole.Bake casserole at 375ºF, uncovered, for 25 minutes, or until bubbly and golden. Remove from oven and let sit for 10 minutes before serving. Serve with extra fresh thyme, if desired.