Chicken Spaghetti Squash with Pesto Alfredo Sauce

Chicken Spaghetti Squash with Pesto Alfredo Sauce is a creamy, cheesy dinner made with roasted spaghetti squash, tender chicken, homemade basil pesto, and a rich Parmesan cream sauce. Everything gets tossed together and can be served right in the roasted squash halves for an easy dinner that still feels a little special.

The pesto Alfredo is what makes this one SO good. Fresh basil, garlic, lemon, and feta are blended into a homemade pesto, then stirred into heavy cream and Parmesan for a sauce that’s creamy, herby, and full of flavor.

• Creamy pesto Alfredo sauce: You get the fresh flavor of pesto with the richness of a Parmesan cream sauce.
• Easy shortcut: Rotisserie chicken means you don’t have to cook another protein.
• Homemade pesto: Fresh basil, garlic, lemon, olive oil, and feta give the sauce tons of flavor.
• Simple dinner: Roast the squash while you make the pesto Alfredo, then toss everything together.
• Fun presentation: Serve it straight from the squash shells or mix everything together in a bowl.

• Spaghetti squash: Roasting it until tender gives you those spaghetti-like strands that soak up the creamy sauce.
• Olive oil: Helps the cut sides of the squash roast and brown.
• Kosher salt and black pepper: Season the squash before roasting.
• Ground nutmeg: Just a tiny amount adds warmth to the creamy Alfredo sauce without making it taste like nutmeg.
• Cooked chicken: I love using rotisserie chicken here because it’s quick and easy. You’ll need 2 cups.
• Heavy cream: Creates the rich base for the pesto Alfredo sauce.
• Parmesan cheese: Freshly grated Parmesan melts into the heavy cream and thickens the sauce.

For the Homemade Pesto

• Fresh basil: Four cups of basil give the pesto its fresh, herby flavor.
• Garlic: Two cloves add plenty of savory garlic flavor.
• Extra virgin olive oil: Helps blend the basil into a smooth pesto.
• Salt: A pinch brings all of the pesto flavors together.
• Feta cheese: Adds a salty, tangy flavor. You can substitute Parmesan cheese if you prefer.
• Lemon: Fresh lemon juice brightens up the pesto and balances the richness of the cream sauce.

The nice thing about this recipe is that the spaghetti squash roasts while you make the pesto Alfredo sauce, so most of the prep happens at the same time.

• Roast the spaghetti squash. Cut the squash in half and remove the seeds. Drizzle each half with 1 tablespoon olive oil and season with salt and pepper. Place cut-side down on a parchment-lined baking sheet and roast at 350°F for 30-45 minutes, until the flesh pulls easily into strands with a fork.
• Make the pesto. Add the basil, garlic, extra virgin olive oil, salt, feta, and fresh lemon juice to a food processor. Blend until finely processed and combined.
• Make the pesto Alfredo sauce. Add the heavy cream, Parmesan, pesto, and nutmeg to a saucepan. Cook over medium-low heat for 10-15 minutes, stirring occasionally, until the sauce has thickened.
• Bring it together. Scrape the spaghetti squash into strands and transfer them to a bowl. Add the cooked chicken and pesto Alfredo sauce, then toss until everything is well coated.
• Serve. Spoon the mixture back into the roasted squash halves for serving, or serve it straight from the bowl. Finish with extra Parmesan if you like.

The spaghetti squash is ready when you can easily drag a fork through the flesh and it separates into spaghetti-like strands. You want it tender but still slightly firm, not soft or mushy. Since squash can vary quite a bit in size, start checking it around the 30-minute mark.

• Don’t overcook it. You want the squash tender enough to pull easily with a fork, but not so soft that the strands turn mushy once you add the sauce.
• Roast it cut-side down. This is my favorite way to get tender spaghetti-like strands while letting the edges get a little golden.
• Check it early. Spaghetti squash can vary quite a bit in size, which is why the roasting time ranges from 30-45 minutes. Start checking around 30 minutes.

• Keep the heat medium-low. You don’t need to boil the cream. Let it gently cook with the Parmesan and pesto until the sauce thickens.
• Use freshly grated Parmesan. It melts into the heavy cream much more smoothly and gives you that creamy Alfredo texture.
• Don’t skip the lemon. The fresh lemon in the pesto cuts through the richness of the cream and Parmesan and keeps the sauce from feeling too heavy.
• Wait until the sauce thickens before combining everything. Spaghetti squash naturally holds some moisture, so you want the pesto Alfredo nice and creamy before adding it to the squash.

This is one of my favorite recipes for using rotisserie chicken. You’ll need 2 cups of cooked chicken, so just shred or chop it while the spaghetti squash is roasting.

You can absolutely use leftover baked, grilled, or roasted chicken instead. Since the chicken is already cooked, you’re really just warming it through when everything gets tossed with the hot pesto Alfredo sauce.

• Make ahead: Roast the spaghetti squash and prepare the pesto ahead of time. Store them separately in the refrigerator, then make the Alfredo sauce and combine everything when you’re ready to serve.
• Storage: Store leftover Chicken Spaghetti Squash in an airtight container in the refrigerator for up to 3-4 days.
• Freezing: I don’t recommend freezing the fully assembled dish. Spaghetti squash can release extra moisture after thawing, and cream-based sauces can separate.
• Reheating: Reheat leftovers gently in a skillet over medium-low heat or in the microwave. If the sauce has thickened in the refrigerator, add a small splash of heavy cream while reheating.