Boneless chicken breast, zucchini, and fresh corn are baked into a creamy, cheesy casserole finished with a crunchy, buttery breadcrumb topping. Made from scratch—no canned soup—this one-pot casserole is wholesome, easy to prepare, and a family favorite.
Casseroles that combine protein and vegetables are my go-to weekday meals, and this chicken zucchini casserole is a great use for summer zucchini. I’ve added sweet corn for natural sweetness and texture. Unlike the quick “dump and bake” versions using canned soup, this recipe builds a real sauce on the stovetop: a little flour to thicken, sour cream and Dijon for tang, and plenty of shredded mozzarella and cheddar for richness. The result is tastier and more nutritious than canned-soup versions.
Because it’s versatile, freezer-friendly, and packed with protein and vegetables, this casserole is excellent for busy families and meal prep.
Ingredients You Need For The Casserole
- Chicken breast – Lean boneless chicken breast, cut into bite-sized pieces.
- Zucchini – Cut into thick slices so they hold texture and don’t turn to mush.
- Corn – Fresh or frozen sweetcorn; fresh adds the best summer flavor.
- Cheese – A blend of shredded cheddar and mozzarella; mozzarella alone also works.
- Sour cream – Adds creaminess and tang to the sauce.
- Flour – Thickens the sauce for a creamy consistency.
- Garlic – Fresh minced garlic; garlic powder can be used if needed.
- Green onion – Use both the white and green parts; regular onion is an acceptable substitute.
- Panko breadcrumbs and butter – For a crispy topping. Panko gives extra crunch; you can stir in a tablespoon or two of grated Parmesan if desired.
Optional additions: broccoli, bell pepper, spinach, or peas for extra vegetables.
Here Is How To Make It – Step by Step
For convenience, use an oven-proof 12-inch skillet so you can cook on the stovetop and finish in the oven. Alternatively, cook in a skillet and transfer to a baking dish.
Searing seasoned chicken first adds flavor. Heat the skillet well before adding the chicken so you get good browning. The chicken does not need to be fully cooked through because it will finish in the oven.
Lower the heat before adding flour and garlic to avoid burning. Stir and scrape the bottom to incorporate any browned bits and prevent sticking.
Can You Make It With Leftover or Rotisserie Chicken?
Yes. This casserole is very forgiving. If using cooked leftover chicken, melt butter in the skillet, sauté garlic, stir in flour briefly, then add chicken stock to create a smooth sauce. Add the shredded chicken, vegetables, sour cream, mustard, and cheese, then top with the buttery breadcrumbs and bake until golden.
Make-Ahead (Assemble Now, Bake Later)
Assemble the casserole in an oven-proof dish and top with the breadcrumb mixture. Cover tightly with two layers of foil or a lid and refrigerate (unbaked) for up to 2 days. Remove from the fridge while preheating the oven and add about 10 minutes to the bake time to account for the chilled dish.
Storing Leftovers
Store leftovers in the refrigerator for up to 3 days. The sauce may thicken when chilled; add a splash of chicken stock while reheating to loosen it. For freshness, consider reheating briefly and sprinkling an extra pan-fried buttery breadcrumb topping before serving.
This casserole is hearty on its own; serve with a light salad, rice, pasta, or roasted potatoes if you want a starch on the side.
More Easy One-Pot Recipes
Chicken Zucchini Casserole
Ingredients
- 1 pound Boneless Chicken Breast, cut into 1.5-inch pieces
- 2 medium Zucchini, thickly sliced
- 1.5 cups Sweetcorn (fresh or frozen)
- 4 tablespoons Butter (divided)
- 2–3 Garlic cloves, minced
- 1 teaspoon Flour
- ½ cup Chicken Stock
- ½ cup Sour Cream
- 1 teaspoon Dijon mustard
- 1½ cups Shredded Cheese (cheddar + mozzarella)
- 2–3 Green onions, chopped (white and green parts)
- 1 cup Panko Breadcrumbs
To season chicken
- 1 teaspoon Italian seasoning
- 1 teaspoon Paprika
- ½ teaspoon Salt and pepper
Instructions
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Preheat oven to 380°F (190°C).
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Combine the remaining melted butter with panko breadcrumbs until evenly coated; set aside.
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Heat 1 tablespoon butter in an oven-proof 12-inch skillet. Toss chicken pieces with Italian seasoning, paprika, salt, and pepper. Add chicken to the hot skillet in a single layer and sear undisturbed for 2–3 minutes, then turn to brown other sides.
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Reduce the heat. Add minced garlic and flour and toss for about a minute, stirring constantly so the flour doesn’t burn.
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Pour in chicken stock and stir, scraping the bottom to release any browned bits and to form a smooth sauce.
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Turn off the heat. Add chopped zucchini, corn, green onion, sour cream, Dijon mustard, and shredded cheese. Stir to combine and smooth the top with a spatula.
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Sprinkle the buttered breadcrumbs evenly over the casserole. Bake in the preheated oven for 20–25 minutes, or until the topping is golden and the casserole is bubbly.