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Chicken Leek and Butternut Squash Bake

There’s something wonderfully nostalgic about a slow, bubbling bake that fills the house with the scent of roasting squash and garlic; this Chicken Leek and Butternut Squash Bake is exactly that kind of comfort. Tender chicken and sweet, caramelized leeks meet creamy sauce and golden breadcrumbs for a dish that feels like a warm embrace on a chilly evening. If you like hearty, one-dish dinners, this is a recipe to make again and again — and it pairs beautifully with other comforting bakes like baked crunchy hot honey chicken.

Why make this recipe
If you’re tired of the same weeknight rotations and want something that feels both special and effortless, this bake solves that problem: it’s layered, comforting, and surprisingly simple. The combination of sweet butternut squash and mild, mellow leeks creates depth without heavy-handed seasoning, while Parmesan and a light breadcrumb topping add crisp texture. It’s a satisfying way to get vegetables, protein, and a cozy sauce all in one dish — perfect for dinner guests or a family meal.

Ingredients

1 tbsp olive oil
1 lb chicken breast, diced
2 cups butternut squash, peeled and cubed
2 large leeks, cleaned and sliced
2 cloves garlic, minced
1 tsp thyme (fresh or dried)
Salt and pepper, to taste
1/2 cup chicken broth
1/2 cup heavy cream or crème fraîche
1/2 cup grated Parmesan cheese
1/4 tsp ground nutmeg
1/2 cup breadcrumbs (optional)
Cooking spray or butter for greasing

Step-by-Step Guide to Making Chicken Leek and Butternut Squash Bake

Preheat and prep

Preheat your oven to 375°F (190°C). Lightly grease a medium-sized baking dish with cooking spray or a little butter so the finished bake releases easily and the edges crisp up nicely.
Peel and cube the butternut squash into roughly 1-inch pieces so they cook evenly; if you prefer quicker cooking, cut them a bit smaller. Clean leeks thoroughly by slicing lengthwise and rinsing between layers to remove grit, then slice into 1/4-inch half-moons.

Sauté the leeks

In a large skillet over medium heat, warm 1 tablespoon olive oil until shimmering but not smoking. Add the sliced leeks and a pinch of salt. Sauté gently, stirring occasionally, until the leeks are soft and beginning to caramelize — about 8–10 minutes. Take your time here: properly softened leeks give the dish sweetness and depth.

Add garlic and herbs

Add the minced garlic and 1 teaspoon thyme (if using fresh, strip the leaves off the stems) to the softened leeks. Cook for another 30–60 seconds, or until fragrant. Season lightly with salt and pepper; remember you’ll add Parmesan later, which brings saltiness.

Brown the chicken

Push the leeks to the side of the skillet (or remove them to a plate briefly) and increase the heat slightly. Add the diced chicken breasts in a single layer if possible. Sear the chicken pieces until they are golden on the outside and just cooked through — about 4–5 minutes depending on size. They don’t need to be fully tender because they’ll finish cooking in the oven, but you want no raw pink on the surface.

Combine with squash and liquids

Stir the leeks and garlic back in with the chicken. Add the cubed butternut squash, then pour in 1/2 cup chicken broth and 1/2 cup heavy cream or crème fraîche. Stir to combine, scraping up any brown bits from the skillet bottom — those are flavor gold. Sprinkle in 1/4 tsp ground nutmeg and taste to adjust salt and pepper. Bring the mixture to a gentle simmer and let it cook for 6–8 minutes, or until the squash is just tender when pierced with a fork. If the mixture thickens too fast, add a splash more broth.

Transfer to a baking dish and top

Transfer the chicken, leek, and squash mixture into your prepared baking dish, spreading it evenly. Sprinkle 1/2 cup grated Parmesan cheese evenly over the top. If you like a crunchy topping, mix 1/2 cup breadcrumbs with a tablespoon of melted butter and sprinkle over the cheese. The breadcrumbs are optional but provide a delightful contrast to the creamy base.

Bake until golden

Place the dish in the preheated oven and bake for 25–30 minutes, or until the top is golden and bubbling and the breadcrumbs (if used) are crisp. If the top browns too quickly, tent loosely with foil for the last 5–10 minutes.

Rest and serve

Remove the bake from the oven and allow it to rest for 5–10 minutes before serving; this helps the sauce set a bit so portions hold together. Garnish with a little extra thyme or chopped parsley if desired.

Why each step matters (quick notes)

Slow-sautéed leeks add sweetness and depth that raw onions can’t quite replicate.
Searing the chicken builds flavor through browning, which improves the overall taste of the sauce.
Simmering the squash in the cream and broth lets it release starches that slightly thicken the sauce for a cohesive, silky texture.
Resting ensures clean slices and a pleasing mouthfeel rather than a running sauce.

Best Way to Store Chicken Leek and Butternut Squash Bake

Refrigerator: Store in an airtight container for 3–4 days at 40°F (4°C) or below.
Freezer: Freeze portions in freezer-safe containers for up to 3 months at 0°F (-18°C). Thaw overnight in the refrigerator before reheating.
Reheating: Reheat single portions in a 350°F (175°C) oven for 15–20 minutes until heated through, or microwave on medium-high in 1–2 minute intervals, stirring between, until hot. For a crisper top, reheat uncovered in the oven or use a quick broil for 1–2 minutes at the end.

Serving Suggestions for Chicken Leek and Butternut Squash Bake

Serve this bake straight from the dish with a crisp green salad dressed in lemon vinaigrette to cut through the creaminess.
For a heartier meal, pair it with buttered new potatoes or a simple pilaf; the squash’s sweetness pairs especially well with nutty grains.
Offer a selection of bread — a crusty baguette or warm dinner rolls — so guests can mop up the delicious sauce.
For wine pairing, try a medium-bodied Chardonnay or a light Pinot Noir; both complement the dish’s creamy texture and roasted squash notes.

Tips to make Chicken Leek and Butternut Squash Bake
Q: How do I keep it moist?
A: Stir a little extra chicken broth (1/4 cup) into the filling if you like a looser sauce, and avoid overbaking — remove it as soon as it’s bubbling and golden.
Q: Can I prep ahead?
A: Yes — assemble the casserole up to the point of adding the breadcrumb/cheese topping, cover, and refrigerate for up to 24 hours. Add the topping and bake when ready.
Q: Can I use other cheeses?
A: Parmesan gives a salty, nutty finish; swapping in Gruyère or a mature cheddar will change the character but work well.

Variations

Vegetarian swap: Replace diced chicken with 2 cups of cooked chickpeas or cubed, roasted cauliflower for a vegetarian version. Use vegetable stock instead of chicken broth.
Autumn gratin: Add thin slices of apple layered with the squash and leeks for a sweet-savory twist; reduce the cream slightly to balance the added moisture.

Notes on ingredient substitution and timing

If you only have frozen butternut squash, thaw and pat dry before adding so excess water doesn’t dilute the sauce.
Low-fat cream or Greek yogurt can be used in place of heavy cream, but the final texture will be tangier and less silky. If using yogurt, add it off the heat to prevent curdling.

FAQs
Q: Can I use bone-in chicken or thighs?
A: Boneless, skinless chicken thighs work beautifully and hold up well to baking; if using bone-in pieces, brown them first and allow longer oven time until the internal temperature reaches 165°F (74°C).
Q: Do I need to peel the butternut squash?
A: Yes, peeling makes for a tender bite. If you prefer, roast the squash cubes separately until tender and toss them into the skillet at the end.
Q: How can I make the topping crispier?
A: Mix the breadcrumbs with a tablespoon of melted butter or olive oil before sprinkling, and finish under a hot broiler for 1–2 minutes while watching closely.
What if I don’t have leeks?

Substitute 1 large yellow onion, thinly sliced; it won’t be quite the same but will still provide a solid foundation of flavor.
Q: Is this dish freezer-friendly once baked?
A: Yes, but the topping can soften slightly. For best results, freeze before baking (assembled), then bake from frozen adding a few minutes to the oven time.

Final notes and serving timing
This bake works wonderfully for weeknight dinners because much of the work (slicing, searing, pre-cooking squash) can be done in advance. For entertaining, assemble in the morning and bake just before guests arrive so it’s hot and golden when you serve. Leftovers reheat well, making this an ideal meal-prep option too.

Conclusion

This Chicken Leek and Butternut Squash Bake is a reliable, comforting dish that balances creaminess, sweetness, and a touch of savory crunch — perfect for any fall or winter evening. For another similar comfort-bake inspiration, see the delightful Slimming Eats’ Chicken, Leek and Butternut Squash Bake, and for a slightly different take with traditional British flavors, consult The English Kitchen’s Chicken with Leeks & Butternut Squash. Enjoy baking, and don’t be afraid to make this recipe your own.