Description

This Cheesy Butternut Squash Casserole is a hearty and comforting fall dish featuring tender roasted butternut squash layered with a creamy kale and garlic sauce, topped with melted Gruyere and a crunchy sourdough walnut crust. Perfect as a side or a vegetarian main, it blends rich cheeses, savory herbs, and a touch of heat from red pepper flakes for a flavorful and satisfying casserole.

Ingredients

Vegetables and Greens

1 medium yellow onion, finely chopped
5 garlic cloves, minced
1 bunch lacinato kale, stems and ribs removed, chopped
2 lbs. peeled and cubed butternut squash

Dairy

1 cup heavy cream
1/3 cup grated Parmesan cheese
2 Tbsp. grated Parmesan cheese
1/2 cup shredded Gruyere or gouda cheese

Oils and Seasonings

4 Tbsp. extra-virgin olive oil, divided
1/4 to 1/2 tsp. crushed red pepper flakes (depending on desired level of heat)
1 Tbsp. Dijon mustard
1 Tbsp. fresh thyme leaves
3/4 tsp. kosher salt
1/2 tsp. black pepper

Others

2 cups torn or roughly chopped sourdough bread
1/3 cup finely chopped walnuts

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Instructions

Preheat and Sauté Aromatics: Preheat your oven to 425ºF. In a large sauté pan, heat 2 tablespoons of olive oil over medium heat. Add the finely chopped onion and cook for 7 to 8 minutes until soft and translucent. Stir in the minced garlic and crushed red pepper flakes, cooking for an additional 2 minutes to release their flavors.
Cook Kale and Make Cream Sauce: Add the chopped lacinato kale to the pan and cook until it softens, about 2 to 3 minutes. Then stir in the heavy cream, 1/3 cup grated Parmesan cheese, Dijon mustard, fresh thyme leaves, kosher salt, and black pepper. Let the mixture simmer for 3 to 5 minutes until it thickens slightly.
Assemble and Bake First Layer: Arrange the peeled and cubed butternut squash evenly in a greased 3-quart baking dish. Pour the kale and cream mixture over the squash, stirring gently to ensure it fills all the crevices. Sprinkle shredded Gruyere cheese evenly on top. Cover the casserole with foil and bake at 425ºF for 30 minutes, or until the squash is nearly fork-tender. If squash is still firm, continue baking for another 10 minutes.
Prepare Topping and Finish Baking: While the casserole bakes, combine torn sourdough bread, chopped walnuts, remaining 2 tablespoons of grated Parmesan cheese, 2 tablespoons olive oil, and a pinch of salt in a bowl. Toss well, massaging the oil into the bread until fully coated. Remove the casserole from the oven and discard the foil. Evenly scatter the sourdough topping over the casserole. Return it to the oven and bake uncovered for an additional 20 minutes, until the squash is tender and the topping is golden and crisp.
Rest and Serve: Allow the casserole to stand for 5 to 10 minutes to set before serving. This helps the flavors meld and the dish to firm up slightly for easier serving.

Notes

If you prefer a milder casserole, reduce the crushed red pepper flakes to 1/4 teaspoon or omit entirely.
To make this casserole gluten-free, substitute sourdough bread with gluten-free bread or crackers for the topping.
Leftovers can be stored covered in the refrigerator for up to 3 days and reheated in the oven for best texture.
For a nut-free version, omit the walnuts or replace them with sunflower seeds or pumpkin seeds.
Ensure the butternut squash is peeled and cut into evenly sized cubes to promote uniform cooking.

Prep Time: 20 minutes
Cook Time: 40 minutes
Category: Casserole
Method: Baking
Cuisine: American