Boneless chicken breast, zucchini, and fresh corn are baked together in a creamy, cheesy casserole topped with a crunchy, buttery breadcrumb crust. Made from scratch—no canned soup—this one-skillet casserole is wholesome, satisfying, and easy to make for weeknight dinners or casual weekend meals.
I’m a fan of casseroles that combine protein and vegetables in one comforting dish, and this chicken zucchini casserole is a perfect summer option when zucchini and sweetcorn are abundant. Instead of the usual canned soup shortcut, this version uses a simple homemade sauce thickened with a bit of flour and enriched with sour cream, Dijon mustard, and a generous mix of mozzarella and cheddar. The result is a tangy, creamy sauce that pairs beautifully with tender chicken and sweet corn.
Because everything cooks in a single oven-proof skillet (or is combined in a skillet and transferred to a casserole), cleanup is minimal and the flavors meld well. It’s freezer-friendly, full of protein and vegetables, and versatile enough to adapt to what you have on hand.
Ingredients You Need For The Casserole
- Chicken breast – Boneless, cut into bite-sized pieces; lean and ideal when combined with cheese.
- Zucchini – Slice into thick rounds so they hold texture and don’t turn mushy while baking.
- Corn – Fresh or frozen sweetcorn works; fresh in season adds a natural sweetness.
- Cheese – A blend of shredded cheddar and mozzarella gives both flavor and melt; use all mozzarella if you prefer.
- Sour cream – Adds creaminess and a slight tang to the sauce.
- Flour – A small amount to thicken the sauce and give it body.
- Garlic – Fresh minced garlic or garlic powder.
- Green onion – Both white and green parts; regular onion can be substituted.
- Breadcrumbs and butter – Panko gives an extra-crunchy topping; toss with melted butter and optional grated Parmesan for extra flavor.
You can also add other vegetables like broccoli, bell pepper, spinach, or peas to vary the dish.
Here Is How To Make It – Step by Step
Use an oven-proof 12-inch skillet to keep this a true one-pot meal. If you don’t have an oven-proof skillet, cook everything in a skillet and transfer to a baking dish before finishing in the oven.
Sear the seasoned chicken in a hot skillet for good browning—this step adds flavor. The chicken does not need to be fully cooked through since it will finish in the oven. After searing, reduce the heat and add minced garlic and flour; stir constantly for a minute so the flour cooks without burning. Add chicken stock and scrape the pan to loosen any browned bits, creating a flavorful base for the sauce.
Turn off the heat and stir in chopped zucchini, sweetcorn, sliced green onion, sour cream, Dijon mustard, and most of the shredded cheese. Smooth the mixture in the skillet, then sprinkle the buttered breadcrumbs evenly over the top. Bake in a preheated 380°F (about 190°C) oven until the topping is golden brown and the casserole is bubbly—about 20–25 minutes.
Can We Make It With Leftover or Rotisserie Chicken?
Yes. This casserole adapts well to leftover cooked chicken. Start by sautéing garlic in butter, add the flour briefly, then whisk in chicken stock to make a smooth sauce. Add the shredded leftover chicken, vegetables, sour cream, mustard, and cheese, then top with the buttery breadcrumbs and bake until heated through and golden.
Make-Ahead (Assemble Now, Bake Later)
Assemble the casserole in an oven-proof dish, sprinkle the breadcrumb topping, then cover tightly with two layers of foil or a lid. Refrigerate the unbaked casserole for up to 2 days. Remove from the fridge while you preheat the oven and add about 10 extra minutes to the baking time to account for the chilled dish.
Storing Leftovers
Refrigerate leftovers for up to 3 days in an airtight container. The sauce may thicken after chilling; when reheating, add a splash of chicken stock to loosen it. For extra crunch when serving, make a small batch of buttery pan-fried breadcrumbs to sprinkle on top.
This casserole is hearty on its own but pairs nicely with a light salad. For a more substantial meal, serve alongside rice, pasta, or roasted potatoes.
More Easy One-Pot Recipes
Chicken Zucchini Casserole
Ingredients
- 1 pound Boneless Chicken Breast cut into 1.5 inch pieces
- 2 medium Zucchini
- 1.5 cup Sweetcorn
- 4 tablespoons Butter
- 2-3 Garlic cloves
- 1 teaspoon Flour
- ½ cup Chicken Stock
- ½ cup Sour Cream
- 1 teaspoon Dijon mustard
- 1.5 cups Shredded Cheese
- 2-3 Green onion (both 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 the oven to 380°F (190°C).
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Prepare the breadcrumb topping by mixing panko with a few tablespoons of melted butter until evenly coated. Set aside.
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Heat 1 tablespoon of butter in an oven-proof 12-inch skillet over medium-high heat. Toss chicken pieces with Italian seasoning, paprika, salt, and pepper. Add chicken in a single layer and sear undisturbed for 2–3 minutes, then turn to brown the other sides.
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Reduce the heat. Add minced garlic and the flour, stirring constantly for about 1 minute so the flour cooks without burning.
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Pour in the chicken stock, scraping the bottom of the skillet to release any browned bits. Stir until smooth.
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Turn off the heat. Stir in chopped zucchini, sweetcorn, sliced green onion, sour cream, Dijon mustard, and most of the shredded cheese. Mix well and smooth the top with a spatula.
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Evenly sprinkle the buttered breadcrumbs over the casserole. Bake in the preheated oven for 20–25 minutes, or until the topping is golden and the casserole is bubbling.