The ultimate savory Butternut Squash Casserole with Parmesan-creamed kale, nutty Gruyere cheese, and a toasted walnut-sourdough topping. This stunning side dish will be the hit of your next holiday gathering.
1/4 to 1/2tsp.crushed red pepper flakes (depending on desired level of heat)
1bunchlacinato kale, stems and ribs removed, chopped
1/3cup, plus 2 Tbsp.grated Parmesan cheese, divided
1Tbsp.fresh thyme leaves
2lbs.peeled and cubed butternut squash
1/2cupshredded Gruyere or gouda cheese
2cupstorn or roughly chopped sourdough bread
1/3cupfinely chopped walnuts
Preheat oven to 425ºF.Heat 2 Tbsp. olive oil in a large sauté pan over medium heat. Once hot, add onion; cook for 7 to 8 minutes, until soft. Stir in garlic and red pepper flakes; cook 2 more minutes.
Stir in kale and cook until softened, about 2 to 3 minutes. Stir in heavy cream, 1/3 cup Parmesan cheese, Dijon mustard, fresh thyme, salt and pepper; simmer mixture until thickened, about 3 to 5 minutes.
Arrange butternut squash in a greased 10.75 x 7.5-inch Staub Ceramic Baking Dish (sub 11x7-inch baking dish). Carefully pour kale mixture over butternut squash, stirring to make sure it gets into all the crevices. Scatter Gruyere cheese overtop.Loosely cover casserole with foil and bake at 425ºF for 20 minutes.
Meanwhile, combine sourdough, walnuts, remaining 2 Tbsp. Parmesan, 2 Tbsp. olive oil, and a small pinch of salt in a medium bowl. Massage oil into bread mixture until well-coated.Remove casserole from oven and discard foil. Scatter sourdough mixture overtop and return casserole to the oven. Bake, uncovered, for 15 more minutes, until the squash is tender and filling is thickened. Broil for the final 1 to 2 minutes for a more golden-brown crust, if desired. Let stand 5 to 10 minutes before serving.
To Make-Ahead: Peel and cube the butternut squash up to 3 days ahead. You can also stem and chop the kale up to 1 day ahead. Refrigerate each in a separate airtight storage container.
Store: Cover and refrigerate leftover casserole for up to 5 days. You can also store individual portions in Zwilling Fresh & Save storage containers to keep the casserole fresh up to five times longer.
To Reheat: For best results, rewarm leftovers in a baking dish in the oven at 350ºF. You can reheat in the microwave in a pinch.
To Freeze: Freeze casserole in an airtight freezer-safe storage container for up to 3 months. Let thaw overnight in the refrigerator before reheating in a 350ºF oven.