Butternut Squash Alfredo Casserole

Picture a casserole dish emerging from the oven, its golden-crisp panko crown crackling as ribbons of steam rise, carrying the sweet, nutty aroma of butternut and Parmesan.

Imagine creamy, sunset-orange sauce clinging to tender pasta shells, each bite silky from a touch of cream and butter, balanced with a whisper of nutmeg and smoked paprika—comfort you can taste before the first forkful.

I love this because it transforms humble squash into a cozy, elegant Alfredo that feels special yet unfussy.

It’s the kind of meal that rescues busy weeknights, anchors lazy Sunday suppers, and wins over picky eaters and veggie-lovers alike.

One rainy evening when schedules collided and appetites soared, this casserole bridged the gap—assembled ahead, baked while we unwound, and delivered warmth to the table right on time.

It’s practical, make-ahead friendly, and crowd-pleasing without shortcuts on flavor.

Ready? Let’s cook!

Why You’ll Love It

• Delivers cozy, creamy comfort with sweet-savory squash Alfredo sauce
• Packs in veggies while staying kid-friendly and indulgent
• Bakes golden and bubbly with irresistible cheesy breadcrumb topping
• Flexes easily: add chicken, peas, mushrooms, or keep vegetarian
• Make-ahead friendly for stress-free weeknights and gatherings

Ingredients

• 12 oz pasta shells or ziti, dried — cook 2 minutes shy of package for best bake texture
• 2 tbsp olive oil — good extra-virgin boosts flavor
• 1 medium yellow onion, chopped — aim for small, even dice
• 3 cloves garlic, minced — fresh cloves, not jarred, for best aroma
• 4 cups butternut squash, peeled and cubed — 1/2-inch cubes cook evenly
• 2 cups low-sodium vegetable broth — low-sodium lets you control seasoning
• 1 cup whole milk — room temp helps sauce blend smoothly
• 1/2 cup heavy cream — adds silky richness
• 1/2 cup grated Parmesan cheese — finely grated melts best
• 1 cup shredded mozzarella cheese — low-moisture, part-skim for good melt
• 2 tbsp unsalted butter — balances sweetness of squash
• 1/4 tsp ground nutmeg — a little goes a long way
• 1/2 tsp smoked paprika — adds gentle smokiness
• 1 tsp kosher salt — adjust to taste after blending
• 1/2 tsp black pepper — freshly ground for brightness
• 1/2 cup panko breadcrumbs — for a crisp, light topping
• 2 tbsp fresh parsley, chopped — reserve some for garnish
• 1/2 cup frozen peas, thawed (optional) — adds color and sweetness
• 1 cup cooked chicken, shredded (optional) — rotisserie works great for convenience

Step-by-Step Method

Preheat & Prep

Preheat oven to 375°F. Grease a 9×13-inch baking dish. Set a large pot of salted water to boil. Gather and measure ingredients. Peel and cube the butternut squash. Chop onion, mince garlic, and shred cheeses. If using peas or chicken, thaw peas and shred cooked chicken. Position rack in the center of the oven.

Par-Cook the Pasta

Boil pasta until 2 minutes shy of package directions. Stir occasionally to prevent sticking. Reserve a small cup of pasta water if you like for thinning later. Drain in a colander. Set aside. Toss with a drizzle of olive oil to prevent clumping if it will sit. Keep warm while making the sauce.

Sauté the Aromatics

Heat olive oil in a large skillet over medium heat. Add chopped onion. Cook until translucent and tender, about 5 minutes. Stir occasionally to avoid browning. Add minced garlic. Cook 30 seconds until fragrant. Don’t burn the garlic. Transfer aromatics to a medium saucepan if using separate vessels for simmering.

Simmer the Squash

Add cubed butternut squash and vegetable broth to the saucepan. Bring to a simmer. Cover and cook until squash is very tender, 12 to 15 minutes. Check with a fork for easy piercing. Remove from heat. Cool slightly to make blending safer. make certain there’s enough liquid left for smooth blending.

Blend the Alfredo Base

Transfer squash and broth to a blender. Add milk, heavy cream, butter, nutmeg, smoked paprika, salt, and pepper. Blend until silky smooth. Work in batches if needed. Vent lid slightly and cover with a towel to release steam. Adjust seasoning to taste. Aim for a velvety, pourable consistency.

Enrich with Cheeses

Return the blended sauce to a clean saucepan over low heat. Whisk in Parmesan until melted and fully combined. Add shredded mozzarella and stir just until melted and smooth. Avoid boiling to prevent splitting. If too thick, thin with warm milk or reserved pasta water, a tablespoon at a time.

Combine Pasta & Add-Ins

Place par-cooked pasta in a large bowl. Pour over the creamy squash Alfredo sauce. Add peas and chicken if using. Toss gently with a wooden spoon to coat evenly. Taste and adjust salt and pepper. make certain even distribution of add-ins so each bite has pasta, sauce, and mix-ins.

Assemble the Casserole

Spread the sauced pasta mixture into the prepared baking dish. Smooth the top for even browning. In a small bowl, toss panko with a drizzle of olive oil and a tablespoon of Parmesan. Sprinkle the breadcrumb mixture evenly over the surface. Cover the dish loosely with foil to prevent over-browning.

Bake to Bubble & Brown

Bake covered for 20 minutes. Remove foil and continue baking 10 to 15 minutes until bubbling and golden on top. Rotate the dish if browning unevenly. If topping needs more color, broil briefly, watching closely. The casserole should be hot throughout and the sauce visibly bubbling at edges.

Rest, Garnish & Serve

Remove from the oven and let rest 10 minutes to set. Sprinkle with chopped fresh parsley and additional Parmesan to taste. Scoop into warm bowls or plates. Serve with a crisp salad or roasted vegetables. Store leftovers covered in the fridge. Reheat gently with a splash of milk to keep creamy.

Ingredient Swaps

• Pasta: Use whole-wheat or gluten-free pasta; shells, ziti, penne, or rigatoni all work.
• Dairy-free: Swap milk/cream with unsweetened oat or cashew milk + 1/2 cup cashew cream; use vegan butter and vegan Parmesan/mozzarella.
• Cheese: Replace mozzarella with fontina, provolone, or mild cheddar; use Pecorino Romano instead of Parmesan (stronger/saltier).
• Protein: Omit chicken for vegetarian; sub cooked Italian sausage, bacon, or chickpeas/lentils for budget-friendly protein.
• Squash: Substitute canned pumpkin or roasted sweet potato if butternut isn’t available.
• Broth: Chicken broth can replace vegetable broth; low-sodium recommended.
• Topping: Use regular breadcrumbs or crushed crackers if panko isn’t on hand; gluten-free panko for GF.
• Add-ins: Swap peas for corn, spinach, or sautéed mushrooms; add kale for a heartier green.
• Spices: Replace smoked paprika with sweet paprika + a pinch of chili powder; add a dash of cayenne for heat.

You Must Know

• Doneness • If the sauce tastes flat after combining cheeses, add 1–2 teaspoons lemon juice or 1/2 teaspoon white wine vinegar; acidity brightens dairy- and squash-heavy sauces. Taste again after 1 minute; it should read savory with a gentle tang.
• Troubleshoot • When the sauce looks grainy or stringy after adding cheeses, lower heat to just-steamy and stir in 1–2 tablespoons warm milk per 30 seconds until glossy; overheating causes protein clumping. Look for a smooth, ribboning pour.
• Flavor Boost • For deeper squash sweetness, roast the cubes to light brown edges (425°F, 20–30 minutes, flip once) before puréeing; caramelization adds nutty notes and concentrates flavor.
• Scale • For 8–10 servings, increase all ingredients by 50% and use a 12×18-inch pan or two 9x13s; extend covered oven time by 5–10 minutes. Visual cue: edges bubbling 1/2 inch in before uncovering.
• Safety • To cool leftovers quickly, spread in a shallow layer no thicker than 2 inches and refrigerate within 2 hours; reheat to 165°F center. This limits bacterial growth and keeps texture creamy.

Serving Tips

• Serve with a crisp arugula salad with lemon vinaigrette to balance richness.
• Plate topped with extra Parmesan, parsley, and a drizzle of good olive oil.
• Pair with garlicky roasted green beans or broccoli for color and crunch.
• Offer warm ciabatta or garlic bread to scoop up the creamy sauce.
• Pour a chilled Pinot Grigio or a light, fruity cider alongside.

Storage & Make-Ahead

Refrigerate leftovers in an airtight container for up to 4 days.

Reheat covered at 325°F or microwave with a splash of milk.

Assemble through topping up to 2 days ahead, cover, and refrigerate.

Add 10–15 minutes to bake time.

Freezes well (baked or unbaked) up to 2 months.

Thaw overnight.

Reheating

Reheat gently: cover and warm in a 325°F oven with a splash of milk.

Microwave in short bursts, covered, stirring between.

On stovetop, low heat, add milk, stir frequently to prevent drying.

Thanksgiving Potluck Staple

After warming leftovers with a splash of milk to keep that sauce silky, I love bringing this Butternut Squash Alfredo Casserole to a Thanksgiving potluck—it’s creamy, golden-topped, and pleasantly autumnal without shouting for attention.

I set it down and watch spoons hover; the Parmesan-crisped panko crackles, steam curls up, and the squash-alfredo sauce glows like candlelight.

I make it ahead to step eleven, chill it, then finish baking at the host’s house, adding a few extra covered minutes.

I tuck foil and chopped parsley in my tote, plus a little extra cheese for showering on top.

It pairs beautifully with tart cranberry sauce, garlicky greens, and roasted turkey.

Vegetarian guests get seconds; meat-eaters add shredded chicken.

Either way, the dish disappears fast.

Final Thoughts

Ready to dig in? Give this cozy Butternut Squash Alfredo Casserole a try as-is, or make it your own with extra veggies, a different melty cheese, or your favorite protein.

Frequently Asked Questions

Can I Freeze the Casserole Unbaked, and for How Long?

Yes—you can freeze it unbaked for up to 2 months. I cool, wrap snugly in foil and plastic, then freeze. Bake from frozen, covered, at 375°F about 45–55 minutes, uncover to brown until bubbly.

How Can I Make This Recipe Dairy-Free Without Losing Creaminess?

Use full-fat coconut milk and cashew cream; I’ll blend soaked cashews with broth until lush. I swap Parmesan with nutritional yeast, add olive-oil roux, finish with silky oat milk. Season warmly—nutmeg, smoked paprika—creamy magic, no dairy.

What’s the Best Gluten-Free Pasta Shape for This Casserole?

Choose gluten-free ziti or rigatoni; they hold sauce and bake beautifully. I’d boil them just shy of al dente, rinse, then toss with sauce. Their sturdy tubes cradle creaminess like warm mittens cupping a mug on snowy nights.

How Do I Scale the Recipe for a Crowd or Half-Batch?

Double or halve every ingredient by weight or volume; keep bake temperature, adjust time. Use two 9x13s for doubling, an 8×8 for halving. Taste the sauce, season warmly, and aim for bubbling edges like candlelit windows.

Can I Prepare the Sauce in an Instant Pot or Slow Cooker?

Yes—you can. I’d sauté onion and garlic on Sauté, pressure-cook squash with broth 5 minutes, quick-release, then blend with dairy and spices. For a slow cooker, cook on High 3–4 hours, blend, finish cheeses gently.