Feta Chicken Spaghetti Squash Casserole (High Protein)

Name: Feta Chicken Stuffed Spaghetti Squash
Prep time: 20 min
Cook time: 55 min
Total time: 1 h 15 min
Cuisine: Greek
Ingredients: 1 medium (3 1/2 lb) spaghetti squash, halved lengthwise and seeded; 1 tablespoon olive oil; 1 1/2 teaspoon kosher salt, divided; 1/2 teaspoon black pepper; 1 7-oz block feta cheese in brine, drained; 1/2 cup sun-dried tomatoes in oil, undrained; 2 large boneless skinless chicken breasts; 1 5-oz package fresh baby spinach (about 5 cups); 4 eggs; 1 tablespoon fresh lemon juice (from 1 lemon); 1/2 teaspoon dried parsley; 1 teaspoon dried oregano; 1/4 teaspoon dried rosemary; 1/4 teaspoon thyme; 1/2 teaspoon dried dill; 1/8 teaspoon ground nutmeg; 4 large garlic cloves, minced (about 2 tablespoons); 2 tablespoons chopped fresh oregano (optional); 1/4 cup grated Parmesan cheese (about 1 ounce)

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Briny feta brings the flavor for this creamy Feta Chicken Spaghetti Squash Casserole!

A mostly hands-off weeknight dinner, this stuffed spaghetti squash recipe has a heaping serving of protein with light Mediterranean flavors similar to Chicken Souvlaki Bowls.

spaghetti squash casserole with feta, spinach, and chicken in a aluminum baking dish with grated Parmesan and a wooden spoon.

Quick Look: Feta Chicken Spaghetti Squash Casserole

⏲️Ready In: 75 Minutes (20 minutes prep, 55 minutes cook)
🍽Servings: 4
🥗Nutrition: ~500 Calories / 46g Protein
🥘Main Ingredients: Spaghetti squash, chicken breast, feta cheese, spinach, eggs, broth, sun-dried tomatoes
📋Dietary Notes: Gluten free, Grain free, High protein

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We're all about high protein meals in our house, and with my busy schedule we often need leftovers on hand.

That's what makes casseroles like Feta Chicken Spaghetti Squash Casserole, Chicken Bacon Ranch Spaghetti Squash Casserole, or Bacon Buffalo Chicken Casserole great - I can whip it up one night and eat the leftovers the next day!

The chicken, feta, and spaghetti squash all bake together before mixing together and finishing with a final quick stint in the oven!

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Quick Look: Feta Chicken Spaghetti Squash Casserole
Key Ingredients
How to make Feta Stuffed Spaghetti Squash
Top Tips from Chelsea
Spaghetti Squash Casserole FAQs
Other Recommended Casseroles
📖 Recipe

Key Ingredients

Ingredients needed for feta chicken spaghetti squash cassserole, with text labels for each ingredient

SPAGHETTI SQUASH: Choose a 3.5-4.5 pound spaghetti squash, which should be pretty average, for this recipe, similar to what I use for Bacon Buffalo Chicken Casserole. Any larger and you overwhelm the casserole with too much squash!

CHICKEN BREAST: Boneless, skinless chicken breast is the way to go. The recipe uses raw chicken, roasted with the squash. But if you have leftover chicken or rotisserie chicken on hand, just stir cooked chicken into the casserole before stuffing the squash for the final bake.

FETA: You'll use a full 6-oz block of feta for this recipe. Look for feta in brine like I used in Baked Feta Cheese with Cranberries, not crumbled feta; dry feta won't melt well, and we want this to get melty so it blends into the sauce for this casserole.

SUN-DRIED TOMATOES: After the first test of this recipe, I felt like the casserole needed a little more flavor, and sun-dried tomatoes fit with the Mediterranean flavors well! I used sun-dried tomatoes packed in oil, but you can use dried as well.

SPINACH: Fresh spinach adds more nutrition and color to this casserole! 5oz of fresh baby spinach is my go-to, but you can use frozen thawed spinach as well.

EGGS: A couple eggs make an easy, protein-boosting way to thicken a casserole without adding a lot more dairy. You can omit the eggs, but the casserole will have a lot of liquid.

See the recipe card for full information on ingredients and quantities.

How to make Feta Stuffed Spaghetti Squash

Note: Make life a little easier by roasting the chicken, feta, and sun-dried tomatoes in the casserole dish you plan to use, keeping the spaghetti squash on its own baking sheet. Then you can mix everything right in the casserole dish while you wait for the spaghetti squash to cool a bit!

Spaghetti squash, chicken, feta cheese, and sun-dried tomatoes on a baking sheet — Step 1: Cut spaghetti squash in half, seed, and place face-down on a baking sheet with chicken breasts, block of feta, and sun-dried tomatoes.

Step 1: Cut spaghetti squash in half, seed, and place face-down on a baking sheet with chicken breasts, block of feta, and sun-dried tomatoes.

Overhead view of roasted spaghetti squash, chicken, feta cheese, and sun-dried tomatoes

Step 2: Roast at 425 degrees F for 40 minutes.

Extra tip: roast the chicken breasts, feta, and sun-dried tomatoes in the casserole dish you plan to use for easy cleanup (and you can mix everything in that dish as well).

A bowl of whisked eggs and Greek seasoning — While other ingredients are roasting, whisk 4 eggs with the Greek spice blend

Step 3: While other ingredients are roasting, whisk the eggs with the Greek spice blend.

Step 4: Combine all ingredients in a large mixing bowl, stirring until feta cheese melts. I get best results when I mix the feta, chicken, and sun-dried tomatoes as soon as they come out of the oven!

Overhead view of uncooked spaghetti squash casserole topped with parmesan cheese — Transfer mixture to a 9x9 baking pan or casserole dish and top with parmesan. Bake for 15 minutes.

Step 5: Transfer mixture to a 9x9 baking pan or casserole dish and top with Parmesan. Bake for 15 minutes.

Top Tips from Chelsea

Stir the feta as soon as it comes out of the oven. If you wait too long, the feta will cool and won't melt. While the spaghetti squash cools, immediately start mixing the feta, sun-dried tomatoes, and chicken together, breaking the chicken up as you go.

Choose the right feta. Block feta with a higher fat content melts the best, just like with Baked Feta Cheese with Cranberries! Don't use feta crumbles; they won't melt.

Mix right in the casserole dish. Keep clean-up a breeze by roasting the chicken, feta, and sun-dried tomatoes right in the casserole dish you plan to use. Then mix those ingredients as soon as they come out of the oven and add the spinach, spaghetti squash strands, and egg mixture right to the casserole!

Closeup of a finished spaghetti squash and feta casserole topped with parmesan cheese

Spaghetti Squash Casserole FAQs

Can I use leftover or rotisserie chicken for this casserole?

Yes! Just stir cooked diced/shredded chicken into the squash/feta/spinach mixture before stuffing the squashes.

You can also prep the chicken separately if you'd like; just

The feta didn't melt well for me in this squash casserole. What happened?

Not all feta melts the same! Opt for blocks of feta, preferably in brine. Feta with a higher fat content will melt better.

And lastly...stir the feta/sun-dried tomatoes/chicken together as soon as they get out of the oven! The first time I tested this casserole, I waited while the spaghetti squash cooled and I was bummed with the results.

The next test, I mixed the feta, sun-dried tomatoes, and chicken together as soon as they came out of the oven while the spaghetti squash cooled. Much better results!