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squash and spinach casserole cut into pieces
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4.78 from 18 votes

Creamy Butternut Squash and Spinach Casserole

Creamy Butternut Squash and Spinach Casserole has just enough cream sauce between its layers to feel rich and festive. It’s a colorful vegetarian and gluten-free side dish that is perfect for the holidays.
Prep Time45 minutes
Cook Time1 hour 15 minutes
Total Time1 hour 15 minutes
Course: Side Dish
Keyword: casserole, squash, Thanksgiving, vegetable side dish
Servings: 12
Author: Jess Smith via Inquiring Chef
Cost: $6.00

Equipment

  • Saute Pan
  • 2 qt Casserole Dish or 9" Cake Pan

Ingredients

  • 1 cup finely diced White Onion
  • 6 Tbsp Unsalted Butter, divided
  • 4 cloves Garlic, finely chopped
  • 1 tsp Kosher Salt
  • 1/2 tsp Black Pepper
  • 1/4 tsp Ground Nutmeg (preferably freshly grated)
  • 8 oz Baby Spinach, roughly chopped
  • 1 cup Heavy / Whipping Cream
  • 1 cup grated Parmesan Cheese, plus extra for topping
  • 1 3 lb Butternut Squash, peeled, seeds removed, and sliced into 1/8-inch slices

Instructions

  • Preheat oven to 350°F / 177°C. Spray a 2-quart casserole dish (or use a 9-inch pie plate or 9-inch cake pan) with nonstick cooking spray or brush with some oil.
  • In a large saute pan over medium heat, melt 4 Tablespoons butter. Add onion and garlic and saute until onion is very soft, 7 to 8 minutes.
  • To onion mixture, add salt, black pepper, nutmeg, and baby spinach. Saute until spinach is wilted (put the lid on to speed it along) and all of the liquid has cooked off, 7 to 8 minutes.
  • Remove spinach from heat and whisk in heavy cream, parmesan cheese, and nutmeg.
  • Layer squash and spinach-cream mixture, using about one fifth of squash and one fourth of spinach for each layer, beginning and ending with squash.
  • Scatter parmesan cheese over top of casserole and dot with pieces of the remaining 2 Tablespoons of butter.
  • If using a baking dish with shallow sides (like a pie plate) place it on a sheet pan to catch any liquid that bubbles over).
  • Cover baking dish tightly with foil and bake until squash is nearly tender, 50 minutes. (Note: If the dish was made ahead and is cold when you transfer it to the oven, add 30 minutes to the initial baking time.)
  • Remove foil and continue baking until casserole is golden brown on top and bubbling around the sides, about 15 minutes more.

Notes

Butternut Squash - If you have a mandolin or the shredding attachment for a food processor, use it to make quick and even work of slicing the squash. This casserole is also great with sweet potatoes, Yukon gold potatoes, or a combination of any of those. 
Spinach - Frozen spinach can be used in place of fresh. Defrost the spinach and thoroughly squeeze out any moisture before adding it to the onions and garlic.
Make Ahead - Assemble the casserole up to 3 days ahead. Allow to come to room temperature before baking. 
Recipe inspired by Butternut Squash and Creamed-Spinach Gratin, Gourmet Magazine, November 2006.  

Nutrition

Calories: 166kcal | Carbohydrates: 3g | Protein: 4g | Fat: 16g | Saturated Fat: 10g | Cholesterol: 50mg | Sodium: 345mg | Potassium: 154mg | Fiber: 1g | Sugar: 1g | Vitamin A: 2320IU | Vitamin C: 7mg | Calcium: 131mg | Iron: 1mg