Pin The first time I made this casserole, my kitchen smelled like autumn had moved in permanently. I had picked up a butternut squash at the farmers market almost impulsively, and now it was sitting on my counter demanding attention. My husband walked in from work, stopped mid hallway, and asked what bakery I was secretly visiting. That rich, savory scent of sausage and herbs mixing with roasting squash filled every corner of our home that evening.
My friend Sarah came over for dinner that first night, pregnant with her second and absolutely exhausted. She took one bite, closed her eyes, and literally moaned into her casserole dish. I made three more batches that month, each for different friends who needed feeding. Something about this combination just wraps around you like a favorite blanket on a November evening.
Ingredients
- 1 medium butternut squash, peeled, seeded, and cut into 1-inch cubes: Fresh squash roasts up sweeter and creamier than precut cubes from the store
- 1 pound Italian sausage, casing removed: Sweet sausage balances the earthy squash, but spicy adds a lovely warmth if you enjoy heat
- 1 medium onion, diced: Red onion adds nice color, but yellow works perfectly fine too
- 2 cloves garlic, minced: Fresh garlic makes a noticeable difference over jarred versions here
- 1 cup cooked quinoa: Quinoa adds protein and a pleasant texture, though rice or couscous work as substitutes
- 3 cups baby spinach: The spinach wilts down dramatically, so do not be afraid of the large volume
- 1 cup shredded mozzarella cheese: Freshly shredded melts more evenly than pre shredded bags
- 1/2 cup grated Parmesan cheese: Adds a salty, nutty finish that ties everything together
- 2 tablespoons olive oil: Extra virgin olive oil adds the best flavor for cooking the sausage and vegetables
- 1 teaspoon dried thyme: Woodsy and earthy, thyme pairs perfectly with both squash and sausage
- 1 teaspoon dried sage: Sage instantly makes everything taste like cozy fall evenings
- 1 teaspoon paprika: Smoked paprika adds depth, sweet paprika adds beautiful color
- 1 cup chicken or vegetable broth: Homemade broth adds the most flavor, but store bought works perfectly
- Salt and pepper, to taste: Taste throughout cooking since the sausage already adds significant salt
- Fresh parsley, for garnish: Optional, but adds a bright pop of color against the golden cheese
Instructions
- Prepare your oven and baking dish:
- Preheat your oven to 375°F and lightly grease a 9x13 inch baking dish with cooking spray or olive oil
- Cook the onion:
- Heat olive oil in a large skillet over medium heat, add diced onion, and cook until translucent about 5 minutes
- Add the garlic:
- Stir in minced garlic and cook for just 1 minute until fragrant, being careful not to burn it
- Brown the sausage:
- Increase heat slightly, add Italian sausage, and cook until browned and cooked through while breaking it apart with a wooden spoon for 7 to 10 minutes
- Add the squash and seasonings:
- Stir in butternut squash, dried thyme, dried sage, paprika, salt, and pepper, cooking for 5 to 7 minutes until the squash begins to soften
- Wilt the spinach and add quinoa:
- Add baby spinach and cooked quinoa, stirring until the spinach wilts completely
- Add the broth and simmer:
- Pour in chicken or vegetable broth and let everything simmer together for 3 to 4 minutes
- Transfer to the baking dish:
- Spread the mixture evenly into your prepared baking dish
- Add the cheese topping:
- Top with shredded mozzarella and grated Parmesan cheese, spreading it evenly across the surface
- Bake covered:
- Cover with aluminum foil and bake for 25 minutes to let everything meld together
- Bake uncovered for the golden finish:
- Remove foil and bake for an additional 15 to 20 minutes until the cheese is bubbly and beautifully golden brown
- Rest and garnish:
- Let the casserole cool for 5 minutes before sprinkling with fresh parsley and serving
Pin 
Last winter, my sister dropped by unexpectedly during a snowstorm, red nosed and shivering. I pulled this casserole straight from the oven, and she stood over the counter eating it with the serving spoon, steam rising into her cold flushed face. Sometimes the simplest meals become the most meaningful memories without any planning at all.
Make It Your Own
I have played around with this recipe more times than I can count, and nearly every variation works beautifully. The base combination of squash, sausage, and cheese is forgiving enough to handle substitutions while still tasting incredible. My oldest daughter now requests this with spicy sausage and extra spinach, a combination that never occurred to me until she started cooking alongside me on Sunday afternoons.
Timing Is Everything
This casserole taught me that some dishes actually improve with a short rest after baking. The five minute cooling period might feel like torture when you are hungry and the house smells amazing, but it makes a real difference in how the slices hold together. I learned this the hard way after serving too soon one night and ending up with a delicious mess on everyone plates instead of neat tidy squares.
Serving Suggestions
A crisp green salad with vinaigrette cuts through the richness perfectly and adds some welcome freshness. Crusty bread for soaking up any extra cheese sauce is never a bad idea either. This casserole has become my go to for potlucks because it travels well and reheats beautifully.
- Make the squash cubes slightly larger if you prefer more texture and bite
- Double the recipe and bake in two dishes so you can freeze one for later
- Let it cool completely before refrigerating leftovers to prevent condensation from making the topping soggy
Pin There is something deeply satisfying about serving a dish that looks impressive but comes together with such straightforward steps. This casserole has earned its permanent place in my regular rotation, and I suspect it might find its way into yours too.
Recipe Questions & Answers
- → Can I make this butternut squash casserole ahead of time?
Yes, you can assemble the entire casserole up to 2 days in advance and refrigerate it. When ready to bake, add a few extra minutes to the cooking time since it will be cold. The flavors often meld better after sitting overnight.
- → What can I substitute for the Italian sausage?
For a vegetarian version, use plant-based sausage crumbles or cannellini beans. You could also substitute ground turkey, chicken, or even chorizo for a different flavor profile. Adjust spices accordingly if using unseasoned meat alternatives.
- → Can I use frozen butternut squash instead of fresh?
Absolutely! Frozen butternut squash works well in this casserole. Thaw it slightly and pat dry before adding to the skillet. You may need to reduce the initial cooking time by a few minutes since frozen squash is typically pre-cut and partially blanched.
- → How do I store and reheat leftovers?
Store leftovers in an airtight container in the refrigerator for 3-4 days. Reheat individual portions in the microwave for 2-3 minutes, or cover the entire dish with foil and warm in a 350°F oven for 15-20 minutes until heated through.
- → Can I freeze this butternut squash sausage bake?
Yes, this casserole freezes well. Assemble the entire dish, wrap tightly in plastic wrap and foil, and freeze for up to 3 months. Thaw overnight in the refrigerator before baking, or add 20-30 minutes to the baking time if cooking from frozen.
- → What vegetables can I add or substitute?
Baby spinach works perfectly, but you can also use kale, Swiss chard, or chopped broccoli. Other great additions include bell peppers, zucchini, or mushrooms. Adjust cooking times as needed—heartier vegetables may need a few extra minutes to soften.