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roasted butternut spinach casserole

Butternut Squash Spinach Casserole

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Prep Time 20 minutes
Cook Time 45 minutes
Resting Time 10 minutes
Total Time 1 hour 15 minutes
Course Main
Cuisine American
Servings 6 servings

Equipment

  • 1 9x13 inch baking dish
  • 1 large skillet
  • 1 Medium saucepan
  • 1 large mixing bowl
  • 1 Whisk
  • 1 Chef's knife
  • 1 Cutting board
  • 1 vegetable peeler
  • 1 Wooden spoon
  • 1 measuring cup set
  • 1 measuring spoon set
  • 1 aluminum foil sheet

Ingredients
  

  • 2 pound butternut squash peeled, seeded, and cubed 1-inch
  • 1 tablespoon olive oil extra-virgin
  • 1 teaspoon kosher salt divided
  • 1/2 teaspoon black pepper divided
  • 1 tablespoon unsalted butter
  • 1 small yellow onion diced
  • 3 clove garlic minced
  • 5 ounce fresh baby spinach roughly chopped
  • 1 cup ricotta cheese whole-milk
  • 1/2 cup sour cream or Greek yogurt
  • 2 large eggs lightly beaten
  • 1/2 cup milk whole or 2%
  • 1/2 teaspoon dried thyme
  • 1/4 teaspoon ground nutmeg
  • 1/4 teaspoon red pepper flakes optional
  • 1 cup shredded mozzarella cheese divided
  • 1/2 cup grated Parmesan cheese divided
  • 1/2 cup panko breadcrumbs
  • 1 tablespoon olive oil for topping
  • 1 tablespoon fresh parsley chopped, for garnish

Instructions
 

  • Preheat the oven to 400°F and lightly grease the 9x13-inch baking dish.
  • Toss the cubed butternut squash with 1 tablespoon olive oil, 1/2 teaspoon salt, and 1/4 teaspoon pepper, spread on the baking dish, and roast for 20 to 25 minutes until just tender.
  • While the squash roasts, heat the butter in a large skillet over medium heat, add the onion with a pinch of salt, and cook 5 minutes until translucent.
  • Stir in the garlic and cook 30 seconds until fragrant, then add the chopped spinach and cook 2 to 3 minutes until wilted; set aside to cool slightly.
  • In a large mixing bowl whisk together ricotta, sour cream, eggs, milk, thyme, nutmeg, remaining 1/2 teaspoon salt, remaining 1/4 teaspoon pepper, and red pepper flakes.
  • Fold the roasted squash, sautéed spinach mixture, 1/2 cup mozzarella, and 1/4 cup Parmesan into the ricotta mixture until evenly combined.
  • Reduce oven temperature to 375°F and transfer the mixture back into the greased baking dish, smoothing the top.
  • In a small bowl combine panko, remaining 1/2 cup mozzarella, remaining 1/4 cup Parmesan, and 1 tablespoon olive oil until crumbly.
  • Sprinkle the breadcrumb-cheese mixture evenly over the casserole and cover the dish loosely with foil.
  • Bake for 20 minutes covered, then remove foil and bake 10 to 15 minutes more until bubbling at the edges and golden on top.
  • Let the casserole rest 10 minutes before garnishing with chopped parsley and serving.

Notes

For the best texture, roast the squash until just fork-tender so it holds its shape in the casserole and doesn’t turn mushy. If using frozen spinach, thaw and squeeze very dry to avoid excess moisture; you can also add an extra tablespoon of Parmesan to absorb any remaining liquid. Swap ricotta with cottage cheese for more protein, or use all Greek yogurt for a lighter version. Add cooked quinoa, farro, or shredded rotisserie chicken to make it heartier, and feel free to season with sage instead of thyme to complement the squash. The casserole can be assembled a day ahead, covered, and refrigerated; add 10 to 15 minutes to the baking time if starting cold. Leftovers keep 3 to 4 days refrigerated and reheat well at 350°F, covered.
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