This cozy chicken and zucchini casserole is my upgraded, written version of the recipe from my video — with a few changes since publishing: a thicker, creamier liaison (roux + cream), extra moisture control for the zucchini, and a mozzarella-parmesan blend for better browning and flavor. It’s weeknight-friendly, crowd-pleasing, and perfect if you’re searching for an easy chicken zucchini bake in Canada or the USA that actually sets beautifully and slices clean.

If you love creamy bakes and classic comfort food, this sits between a vegetable gratin and a chicken casserole. Pair it with a crisp salad or potatoes for a complete dinner. For salad ideas, try my Homemade Ranch Dressing or the lighter Caesar Salad Dressing without Mayonnaise. If you prefer a potato side instead of sweet potatoes in the dish, Parisian Potatoes are elegant and quick.

Why you’ll love it

Creamier, better set interior. We increase the roux slightly and simmer off more water from zucchini so the gratin slices clean.
Balanced flavor. A touch of Dijon or lemon brightens the sweetness of sweet potato.
Family-friendly. Familiar cheese pull from mozzarella with the flavor boost of parmesan.
Flexible. Swap in regular potatoes, add spinach, or use leftover rotisserie chicken.

(Based on my YouTube video — with a few upgrades since its release for texture, moisture balance, and flavor depth.)

Ingredients (Metric + US)

Serves 4–6

Chicken breasts, boneless skinless: 700–800 g (1½–1¾ lb), cut in 2–3 cm (1-inch) cubes
Sweet potatoes, peeled & sliced: 800 g (≈1¾ lb)
Zucchini, peeled & diced: 2 medium (≈500–600 g / 1.1–1.3 lb)
Yellow onions, thinly sliced: 2 medium (≈350 g / 12 oz)
Garlic, minced: 2 large cloves
Mozzarella, shredded: 150 g (≈1½ cups packed)
Parmesan, finely grated: 50 g (½ cup)
Heavy cream (35%): 250–300 ml (1–1¼ cups)
Butter or olive oil (for roux + sauté): 3–4 tbsp total
All-purpose flour (or gluten-free blend): 3 tbsp
Chicken broth or milk: 50–100 ml (3–6 tbsp), as needed for sauce consistency
Dijon mustard OR lemon juice: 1 tsp Dijon or 1–2 tsp lemon juice
Fresh basil: 10–15 leaves, chopped (plus a few whole leaves to garnish)
Fine sea salt & freshly ground black pepper
For boiling sweet potatoes: 2.5 L (2½ qt) water + 25 g (1½ tbsp) salt

Optionally add a pinch of nutmeg or smoked paprika for warmth.

Step-by-step (Improved Method)

Boil the sweet potatoes
Place slices in cold salted water (2.5 L + 25 g salt). Bring to a boil; simmer until just tender, ~20 minutes. Drain well and keep warm.

Sauté the zucchini hot & dry
Heat a large skillet on medium-high with 1 tbsp oil. Add zucchini, season with salt and pepper. Sauté 7–9 minutes to drive off moisture and lightly color. Transfer to a tray to steam off excess moisture.

Brown chicken + aromatics
In the same skillet, add 1 tbsp oil. Sear chicken cubes 6–8 minutes until lightly browned. Add onions and cook 3–4 minutes, then garlic for 30 seconds. Season well.
Optional but recommended: Deglaze with 60 ml (¼ cup) chicken broth or dry white wine; reduce to nearly dry.

Make the creamy liaison (roux + cream)
In a small saucepan, melt 2 tbsp butter. Whisk in 3 tbsp flour, cooking 1–2 minutes. Gradually whisk in 250–300 ml cream plus 50–100 ml broth/milk until you get a thick, spoon-coating sauce. Season to taste, then whisk in 1 tsp Dijon (or lemon juice). Stir in half the basil. Simmer 30–60 seconds to marry flavors.

Combine
In a large bowl, gently combine sweet potatoes, zucchini, chicken-onion mixture, and the sauce. Fold in a small handful of mozzarella (≈30–50 g) for interior stretch. Taste and adjust salt/pepper/acid.

Assemble & bake
- Transfer to a buttered 30 × 20 cm (13 × 9-inch) gratin dish.
- Top with mozzarella + parmesan.
- Bake uncovered at 190°C / 375°F for 25–30 minutes until bubbling.
- Switch to broil for 2–5 minutes for deep color.
- Rest 10 minutes before slicing. Garnish with remaining basil.

Love cheesy bakes? See Traditional Gratin Dauphinois or my Creamy Mozzarella Parmesan Pasta.

Substitutions

Potatoes: Swap sweet potatoes for Yukon Gold or Russet (same weight).
Cheese: Use Gruyère or Emmental instead of mozzarella + parmesan.
Protein: Cooked shredded rotisserie chicken works; fold it in during assembly.
Cream: Half-and-half can work; extend roux with broth to keep sauce thick.
Gluten-free: Use a GF all-purpose blend for the roux, or thicken with Beurre Manié.

Tips & Make-Ahead

Dry the zucchini. The extra sauté time prevents a watery gratin.
Thick sauce = clean slices. Aim for nappe consistency before combining.
Make-ahead: Assemble, cover, and chill up to 24 hours; bake 10–15 minutes longer.
Reheat: 160°C/325°F, covered, 15–20 minutes; uncover to re-crisp cheese.

FAQ

Can I skip the Dijon/lemon?
You can, but a small acidic note balances the sweetness of sweet potatoes and richness of cream.

Can I add spinach or mushrooms?
Yes. Sauté first to drive off moisture, then fold in.

Will mozzarella alone be bland?
It’s melty but mild. The parmesan blend helps with salt, flavor, and browning.

What if I only have chicken thighs?
Great choice — more forgiving and juicy. Trim and cut as directed.

Suggested sides & similar recipes

Homemade Greek Salad
Homemade Garlic Butter (for warm bread)
Homemade Tomato Sauce with Fresh Tomatoes
Chicken Piccata (30 minutes)
Easy Chicken Milanese
Easy Chicken Fried Rice (for leftovers another night)
American Goulash
One-Pot Creamy Beef & Tomato Pasta
Recipe Index (explore more weeknight dinners)