Spaghetti Squash Au Gratin

Spaghetti Squash Au Gratin: Creamy Cheesy Casserole

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Warm, cheesy, and wonderfully comforting, Spaghetti Squash Au Gratin transforms humble autumn squash into a silky, golden-bubbly casserole that’s perfect for weeknights or holiday tables. Beginner cooks will love how the squash’s tender, noodle-like strands pair with a creamy cheese sauce and crisp gratin topping — all without feeling fussy.

Spaghetti Squash Au Gratin: tender strands coated in a rich cheese sauce with a golden breadcrumb crust.

Why You’ll Love ThisSpaghetti Squash Au Gratin Recipe

  • Quick and easy to prepare — roast the squash, mix a simple cheese sauce, and bake until golden…
  • Uses simple, wholesome ingredients you likely already have on hand…
  • Perfect for family meals or entertaining — satisfying enough to serve as a main or a show-stopping side…

A Little Background

Au gratin casseroles are a classic way to turn simple produce into something indulgent. Spaghetti squash is a seasonal favorite for those seeking a lighter alternative to pasta: when roasted, its flesh separates into tender, spaghetti-like strands that soak up sauces beautifully. This au gratin approach blends that delicate texture with a creamy, cheesy binder and a crispy topping for contrast — ideal in fall and winter when squash is at its best.

Key Ingredients for perfect Spaghetti Squash Au Gratin

  • Spaghetti squash: Roasted and shredded into tender strands that mimic noodles.
  • Sharp cheddar: Adds bold, melty flavor to the creamy sauce.
  • Parmesan cheese: Offers salty, nutty depth and helps form a golden crust.
  • Milk or cream: Creates a smooth, rich base for the cheese sauce.
  • Breadcrumbs or panko: Provides a crunchy gratin topping for texture contrast.

Step-by-Step Instructions to make Spaghetti Squash Au Gratin

  1. Preheat your oven and prepare the squash: halve the spaghetti squash lengthwise, remove the seeds, brush the cut sides with oil, and roast until the flesh is tender and easily shredded with a fork.
  2. Shred the squash flesh: once cool enough to handle, use a fork to scrape the strands from each half and transfer them to a large bowl; season lightly with salt and pepper.
  3. Make a simple cheese sauce: melt butter in a saucepan, whisk in a little flour to form a roux, then slowly add milk (or cream) until smooth and thickened. Remove from heat and stir in shredded cheddar and grated Parmesan until melted and silky. Season with salt, pepper, and a pinch of nutmeg if desired.
  4. Toss and assemble: combine the spaghetti squash strands with the cheese sauce so the strands are evenly coated. Spoon the mixture into a buttered baking dish, press to level, and sprinkle breadcrumbs and a little extra cheese on top for a gratin finish.
  5. Bake until golden: place the dish in the oven and bake until the top is bubbling and nicely browned — this creates a crisp, flavorful crust over the creamy squash.
  6. Rest and serve: let the casserole rest briefly after baking so it sets slightly, then serve warm as a comforting side or a lighter main course.

Pro Tips & Variations

  • Practical cooking tip: roast the squash cut-side down on a baking sheet to concentrate steam and speed up cooking, or punch a few vent holes and microwave whole for a faster prep.
  • Storage or reheating suggestion: refrigerate leftovers in an airtight container for up to 3–4 days; reheat covered in the oven to keep the gratin topping crisp, or microwave for convenience.
  • Optional variations: stir in cooked bacon, sautéed mushrooms, or baby spinach for added flavor and texture; swap cheeses (Gruyère or fontina work beautifully) to change the character of the dish.

Serving Suggestions

Pair this Spaghetti Squash Au Gratin with a crisp green salad and roasted chicken for a balanced meal, or serve alongside grilled steaks or pork chops for a holiday-style spread. A bright white wine or a light-bodied red complements the creamy, cheesy flavors nicely.

Spaghetti Squash Au Gratin

Spaghetti Squash Au Gratin

Creamy, cheesy, and irresistibly golden on top, this Spaghetti Squash Au Gratin turns tender squash strands into a cozy, lighter twist on classic gratin. It’s simple enough for weeknights yet special enough for holidays and potlucks.
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Prep Time 20 minutes
Cook Time 1 hour
Resting Time 10 minutes
Total Time 1 hour 30 minutes
Course Main Course, Side Dish
Cuisine American
Servings 6 servings
Calories 270 kcal

Equipment

  • Baking Sheet
  • Chef’s knife
  • Large saucepan
  • Whisk
  • 2-quart baking dish
  • Colander

Ingredients
  

Au Gratin Base

  • 1 medium spaghetti squash about 3 lb (1.4 kg)
  • 1 tbsp olive oil
  • 2 tbsp unsalted butter
  • 1/2 cup yellow onion, finely chopped
  • 2 cloves garlic, minced
  • 2 tbsp all-purpose flour
  • 1 1/2 cups milk (whole or 2%)
  • 1 1/2 cups sharp cheddar, shredded
  • 1/2 cup Parmesan cheese, grated
  • 1/2 tsp kosher salt plus more to taste
  • 1/4 tsp black pepper
  • 1/4 tsp ground nutmeg optional

Topping

  • 1/2 cup panko breadcrumbs
  • 1 tbsp unsalted butter, melted
  • 1/4 cup Parmesan cheese, grated
  • 1 tbsp fresh parsley, chopped optional garnish

Instructions
 

  • Preheat oven to 400°F (200°C). Halve the spaghetti squash lengthwise, scoop out the seeds, brush the cut sides with olive oil, and season lightly with salt and pepper. Place cut-side down on a lined baking sheet and roast 35–45 minutes, or until the flesh is tender.
  • When cool enough to handle, use a fork to scrape the flesh into spaghetti-like strands. Transfer to a bowl and let excess moisture drain in a colander (or blot with a clean towel).
  • Make the sauce: In a large saucepan over medium heat, melt the butter. Add the chopped onion and cook until softened, 3–4 minutes. Stir in the garlic for 30 seconds. Whisk in the flour and cook 1 minute. Slowly stream in the milk, whisking constantly, and simmer until thickened and silky, 3–5 minutes.
  • Remove from heat and stir in cheddar and Parmesan until melted. Season with salt, pepper, and nutmeg (if using).
  • Combine the squash strands with the cheese sauce and transfer to a greased 2-quart baking dish, smoothing the top.
  • Mix the topping: toss panko with melted butter and Parmesan, then sprinkle evenly over the casserole.
  • Bake at 400°F (200°C) for 15–20 minutes, until bubbling and golden. For extra color, broil 1–2 minutes, watching closely.
  • Rest 10 minutes before serving. Garnish with parsley and enjoy warm as a side or light main.

Notes

Make-ahead: Roast the squash and prep the sauce up to 2 days in advance; refrigerate separately. Assemble just before baking, adding 5–10 extra minutes if chilled.
Shortcuts: Microwave the whole squash (pierced several times) 5–10 minutes to soften before halving, then finish roasting. Or fully microwave the halves cut-side down in a dish with a splash of water until tender.
Substitutions: Swap cheddar for Gruyère or fontina; use half-and-half for a richer sauce. For a gluten-free topping, try crushed pork rinds or gluten-free panko and replace flour with a 1:1 GF blend or cornstarch slurry.
Leftovers: Store covered in the fridge up to 3–4 days. Reheat in a 350°F (175°C) oven until warmed through to keep the topping crisp, or microwave for a quick reheat.

Nutrition

Calories: 270kcalCarbohydrates: 20gProtein: 12gFat: 16gSaturated Fat: 9gCholesterol: 45mgSodium: 520mgPotassium: 480mgFiber: 3gSugar: 7gVitamin A: 520IUVitamin C: 9mgCalcium: 320mgIron: 1.3mg
Keyword Comfort Food, Spaghetti Squash Au Gratin, Vegetable Casserole
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