Introduction

Remember those chilly evenings when you just wanted something warm, comforting, and utterly delicious to fill your kitchen with amazing aromas? This Spaghetti Squash Casserole is exactly that! It’s a hug in a bowl, a dish that feels like it’s been passed down through generations, but guess what? It’s surprisingly simple to whip up, making it perfect for those busy weeknights when you still want a wholesome, satisfying meal.

Why You’ll Love This Recipe

Super Speedy: While the squash roasts, you’ll be busy making the flavorful turkey and creamy sauce. It’s efficient cooking at its finest!
Effortlessly Easy: No fancy techniques here! Just simple steps that lead to a truly fantastic meal.
Perfect for Gifting: Made a double batch? This casserole is fantastic for sharing with neighbors, friends who just had a baby, or anyone who could use a little homemade love.
Guaranteed Crowd-Pleaser: Even picky eaters will be asking for seconds of this creamy, cheesy, and veggie-packed dish. It’s a wholesome twist on comfort food!

Ingredients

Let’s gather our goodies! Don’t be intimidated by the list; it all comes together beautifully.

1/2 pound ground turkey: A leaner protein that cooks up beautifully and soaks up all those wonderful flavors.
2 (3-pound) spaghetti squash: Our star! These beautiful gourds transform into delightful spaghetti-like strands.
2 cups packed baby spinach leaves: A little green goodness to sneak in some extra nutrients.
6 cloves garlic, minced: Because everything is better with plenty of garlic!
1/2 teaspoon granulated garlic: For an extra punch of garlic flavor.
1/2 teaspoon granulated onion: Deepens the savory notes of the dish.
1 medium onion, chopped: The classic aromatic base for so many good things.
1 1/2 tablespoons fresh sage leaves, chopped: Sage brings such a warm, earthy, and slightly peppery note. It’s like fall in a bite!
1 teaspoon fresh thyme leaves, chopped: Thyme adds a subtle floral and lemony hint that complements the sage perfectly.
2 teaspoons black pepper: For a gentle kick and warmth.
5 tablespoons all-purpose flour: This is our thickener for that luscious sauce.
1 teaspoon Italian seasoning: A handy blend that brings together oregano, basil, and other Italian favorites.
1 pinch nutmeg: A little secret ingredient that adds a subtle warmth and depth to creamy sauces. You won’t even taste it directly, but it makes a difference!
2 teaspoons salt: To bring out all the flavors.
1/4 teaspoon white pepper: Adds a delicate peppery note without visible specks.
1 tablespoon olive oil: For sautéing our aromatics.
3 tablespoons unsalted butter: The foundation of our rich, creamy sauce.
1 cup grated Gruyere cheese: Oh, Gruyere! It’s nutty, slightly sweet, and melts like a dream. Adds such a sophisticated flavor.
3 cups whole milk: For that irresistible creamy texture.
1/2 cup crispy fried onions: The crunchy topping that everyone fights over!

How to Make It

Ready to create some magic? Let’s get cooking!

Preheat Your Oven: First things first, let’s get that oven to 400°F (200°C).
Roast the Squash: Carefully halve your spaghetti squash lengthwise. Scoop out those stringy seeds (you can roast them separately if you like!). Place the halves cut-side down on a baking sheet. Pop them in the oven for about 45-60 minutes, or until they’re nice and tender when you poke them with a fork.
Brown the Turkey: While the squash is doing its thing in the oven, grab a large skillet and cook your ground turkey over medium heat. Brown it all up, breaking it apart as it cooks. Once it’s nicely browned, drain off any excess fat.
Sauté the Onions: Toss your chopped onion into the skillet with the turkey. Let them cook until they start to soften, which usually takes about 5 minutes.
Aromatics and Herbs: Now, add that minced garlic, granulated garlic, granulated onion, chopped sage, and thyme to the skillet. Stir and cook for just 1 minute more until everything smells absolutely divine.
Build the Flavor Base: Sprinkle in the flour, Italian seasoning, nutmeg, black pepper, white pepper, and salt. Stir it all together and cook for another 1-2 minutes, stirring constantly. This helps cook out the raw flour taste.
Whisk in the Milk: Gradually whisk in the whole milk, making sure to get all those little lumps out. Bring the mixture to a gentle simmer and let it cook, stirring often, until it thickens up nicely, about 5-7 minutes. It should be a lovely, creamy sauce!
Cheese and Spinach: Stir in your baby spinach leaves and about half of your grated Gruyere cheese. Keep stirring until the spinach wilts and the cheese is all melty and glorious.
Shred the Squash: Once your spaghetti squash is tender, carefully remove it from the oven. Using a fork, gently scrape and shred the strands from the shell. It should come away easily! Discard the shells – they’ve done their job.
Combine Everything: Now, add that beautiful shredded spaghetti squash right into your skillet with the turkey and creamy sauce. Give it all a good stir to make sure everything is coated and combined.
Assemble the Casserole: Pour this delicious mixture into a 9×13 inch baking dish. Spread it out evenly.
Top it Off: Sprinkle the remaining Gruyere cheese all over the top, followed by that wonderful pile of crispy fried onions.
Bake to Perfection: Pop it back into the oven for 20-25 minutes, or until the casserole is bubbly around the edges and the topping is golden brown and irresistible.

Substitutions & Additions

Feeling adventurous? Want to switch things up? I love that spirit!

Meat Swap: Ground chicken or even lean ground beef would work wonderfully here. For a vegetarian option, you could omit the meat entirely and add more veggies like mushrooms or broccoli florets.
Cheesy Fun: Don’t have Gruyere? Sharp cheddar, Monterey Jack, or a blend of Italian cheeses would be fantastic.
Herb Power: If you don’t have fresh sage or thyme, you can use 1 teaspoon of dried sage and 1/2 teaspoon of dried thyme, but fresh really does add a special brightness.
Veggie Boost: Feel free to toss in some sautéed mushrooms, bell peppers, or even some frozen peas with the spinach.
Spice it Up: A pinch of red pepper flakes can add a little warmth if you like a touch of heat.

Tips for Success

A few little tricks up my sleeve to make this recipe even more of a breeze!

Squash Prep: Roasting spaghetti squash whole is an option too! Just prick it a few times with a fork and roast until tender. It can take a bit longer, but it’s less messy if you’re worried about cutting it.
Don’t Overcook the Sauce: Keep an eye on the sauce as it thickens. You want it creamy, not gloopy.
Crispy Onions are Key: For the best crunch, add them just before baking. If you’re prepping ahead, save them until you’re ready to pop it in the oven.
Prep Ahead: You can totally assemble the entire casserole (up to step 12) the day before. Cover it tightly and store it in the refrigerator. When you’re ready to bake, let it sit at room temperature for about 30 minutes before baking, and you might need to add a few extra minutes to the baking time.

How to Store It

Got leftovers? Lucky you!

Store any leftover Spaghetti Squash Casserole in an airtight container in the refrigerator for up to 3-4 days. When you’re ready to enjoy it again, simply reheat it in the oven or microwave until warmed through. I find it’s even more delicious the next day!

FAQs

Got a question? I’ve got an answer!

Can I make this ahead of time? Absolutely! You can assemble the casserole up to the point of adding the final cheese and crispy onions the day before. Keep it covered in the fridge and bake when ready, adding a few extra minutes to the cooking time.
What can I serve with this casserole? It’s pretty much a meal in itself, but a simple side salad with a light vinaigrette or some crusty bread for dipping would be lovely.
Is spaghetti squash healthy? Yes! It’s a fantastic low-carb alternative to pasta, packed with vitamins and fiber.

Cozy Spaghetti Squash Casserole

A warm, comforting, and utterly delicious Spaghetti Squash Casserole that is surprisingly simple to whip up, making it perfect for busy weeknights. It's a wholesome twist on comfort food, packed with flavor and creamy goodness.

Print Recipe Pin Recipe

Prep Time 20

Cook Time 1 10

Servings 6

Equipment

Baking Sheet
Large skillet
9x13 inch baking dish

Ingredients

Main Ingredients

0.5 pound ground turkey leaner protein
2 spaghetti squash 3-pound each
2 cups baby spinach leaves packed
6 cloves garlic minced
0.5 teaspoon granulated garlic
0.5 teaspoon granulated onion
1 medium onion chopped
1.5 tablespoons fresh sage leaves chopped
1 teaspoon fresh thyme leaves chopped
2 teaspoons black pepper
5 tablespoons all-purpose flour thickener
1 teaspoon Italian seasoning
1 pinch nutmeg for depth
2 teaspoons salt
0.25 teaspoon white pepper
1 tablespoon olive oil for sautéing
3 tablespoons unsalted butter for sauce
1 cup Gruyere cheese grated, divided
3 cups whole milk for creamy sauce
0.5 cup crispy fried onions for topping

Instructions

Preheat your oven to 400°F (200°C).
Halve the spaghetti squash lengthwise, scoop out seeds, and place cut-side down on a baking sheet. Roast for 45-60 minutes until tender.
0.5 pound ground turkey
While squash roasts, brown ground turkey in a large skillet over medium heat. Drain excess fat.
0.5 pound ground turkey
Add chopped onion to the skillet and cook until softened, about 5 minutes.
0.5 pound ground turkey
Add minced garlic, granulated garlic, granulated onion, chopped sage, and thyme. Cook for 1 minute until fragrant.
0.5 pound ground turkey
Sprinkle in flour, Italian seasoning, nutmeg, black pepper, white pepper, and salt. Stir and cook for 1-2 minutes.
0.5 pound ground turkey
Gradually whisk in whole milk. Bring to a simmer and cook, stirring often, until thickened, about 5-7 minutes.
0.5 pound ground turkey
Stir in spinach and half of the Gruyere cheese until spinach wilts and cheese melts.
0.5 pound ground turkey
Shred the cooked spaghetti squash strands from the shells using a fork.
0.5 pound ground turkey
Add the shredded squash to the skillet with the turkey and sauce. Stir to combine.
Pour the mixture into a 9x13 inch baking dish and spread evenly.
Sprinkle the remaining Gruyere cheese and crispy fried onions over the top.
0.5 pound ground turkey
Bake for 20-25 minutes, until bubbly and golden brown.

Notes

This casserole can be assembled a day in advance and baked when ready. Let it sit at room temperature for about 30 minutes before baking if refrigerated. Leftovers can be stored in an airtight container in the refrigerator for up to 3-4 days and reheated in the oven or microwave.