Creamy Chicken Rice Casserole with Mushrooms and Spinach

I love a good kitchen hack, so here’s my little chef’s secret: swap the canned soup for a real, silky white sauce and you’ll upgrade this casserole from “weeknight rescue” to “I could serve this to guests” in one swoop. I stumbled on this while trying to coax more flavor out of leftover rotisserie chicken — a quick roux, a splash of broth, and a handful of sharp cheese changed everything. The mushrooms sing when they hit the hot pan, the spinach wilts into glossy green ribbons, and the whole house smells like comfort with a little restaurant polish. If you want creamy, cozy, and honestly impressive, this is your new go-to.

Quick Facts

• Yield: Serves 6
• Prep Time: 20 minutes
• Cook Time: 40 minutes
• Total Time: 60 minutes

Why This Recipe is Awesome

This casserole balances creamy sauce, tender **chicken**, earthy **mushrooms**, and bright **spinach** — all baked with a slightly crunchy top. It tastes rich without being gloopy, has pockets of gooey cheese and golden edges, and fills the kitchen with irresistible savory smells. It’s so easy even your oven can’t mess it up, and it makes fantastic leftovers (if it even lasts that long).

Ingredients

For the Main Dish:

• 1 1/2 cups long-grain white rice (uncooked)
• 3 cups low-sodium chicken broth
• 1 lb (about 3 cups) cooked chicken, shredded or diced (rotisserie works great)
• 8 oz cremini or button mushrooms, sliced
• 4 cups fresh spinach (packed)
• 1 medium yellow onion, diced
• 3 cloves garlic, minced
• 2 tbsp olive oil
• 2 tbsp butter
• Salt and black pepper to taste
• 1/2 tsp dried thyme
• 1/4 tsp smoked paprika (optional)
• 1 cup sharp cheddar, shredded
• 1/2 cup grated Parmesan

For the Sauce / Garnish (if applicable):

• 2 tbsp butter
• 3 tbsp all-purpose flour
• 1 1/2 cups milk (whole or 2%)
• 1/2 cup sour cream (or Greek yogurt)
• 1/2 cup chicken broth (extra, if needed)
• 1/2 cup breadcrumbs (or crushed crackers) mixed with 1 tbsp melted butter for topping

How I Make It

Step 1:

Preheat the oven to 375°F. Heat a large skillet over medium-high heat and add 2 tbsp olive oil. Toss in the **sliced mushrooms** and a pinch of salt; let them sizzle and brown — don’t stir too often so they get color. After 5–7 minutes, add the **diced onion** and cook until translucent. Stir in the **garlic** until fragrant, about 30 seconds. Smell that nutty mushroom-onion aroma? That’s flavor building.

Step 2:

Lower the heat to medium and push the veggies to one side of the pan. Add 2 tbsp butter and let it melt, then sprinkle in 3 tbsp flour. Whisk constantly for about a minute to form a roux — it should smell toasty, not raw. Gradually whisk in 1 1/2 cups milk and 1/2 cup chicken broth until smooth and slightly thickened. Stir in 1/2 cup sour cream, salt, pepper, thyme, and a pinch of smoked paprika.

Step 3:

Fold in the **shredded chicken**, **fresh spinach**, and the cooked rice. The spinach will wilt into glossy green ribbons; give it a minute. Taste and adjust seasoning — the sauce should taste seasoned but not salty, since the cheese adds salt later. If the mixture looks too dry, add up to 1/4 cup extra chicken broth.

Step 4:

Spoon everything into a greased 9×13-inch baking dish. Sprinkle the **sharp cheddar** and **Parmesan** evenly on top, then scatter the breadcrumb mixture for a golden crunch. Bake at 375°F for 35–40 minutes until bubbly and the top shows golden spots. You’ll hear gentle bubbling and catch a warm, toasty aroma — that’s your cue. Let it rest 10 minutes before serving so the casserole firms up.

Step 5:

Scoop generous portions and garnish with extra chopped parsley or a squeeze of lemon if you want brightness. Check the chicken reaches 165°F with a probe if you’re unsure — safety first, flavor still wins.

Pro Tips

• Use leftover rotisserie chicken to save time and add flavor. Shred it while it’s warm so it absorbs sauce better.
• If your casserole looks dry before baking, stir in up to 1/2 cup extra broth — rice soaks liquid differently depending on brand.
• For a creamier texture, swap 1/4 cup sour cream for 1/4 cup cream cheese and whisk until smooth.
• Don’t skip browning the mushrooms — that Maillard flavor makes this casserole sing.

Common Mistakes to Avoid

• Skipping preheating: Classic rookie move. It changes texture and bake time.
• Overmixing: Leads to dense or chewy results. Mix until just combined.
• Guessing cook time: Always use visual cues or a timer, not just vibes.
• Overcrowding pans: Give your food some breathing room to crisp properly.

Alternatives & Substitutions

• Swap chicken for firm tofu or cooked white beans for a vegetarian twist; texture shifts but the casserole still thrills.
• Use brown rice (cooked) instead of white rice; you’ll need to pre-cook it and may reduce baking time slightly.
• Replace sour cream with full-fat coconut yogurt for a dairy-free option — expect a faint coconut note.
• Gluten-free? Use a gluten-free flour for the roux and gluten-free breadcrumbs.

Variations & Tips

• Spicy: Add 1 tsp chili flakes or a diced jalapeño with the onions.
• Kid-friendly: Skip the mushrooms and add sweet corn or peas for milder flavors.
• Mediterranean twist: Swap cheddar for feta and add sun-dried tomatoes and olives.
• One-pot shortcut: Use 2 cups cooked rice and bake only to meld flavors — skip the extra liquid.
• Herby uplift: Stir in fresh basil or tarragon just before serving for a bright finish.
• Crunchy twist: Top with crushed potato chips instead of breadcrumbs for nostalgic texture.

FAQ (Frequently Asked Questions)

Can I make this ahead of time?

Yes! Assemble the casserole, cover, and refrigerate up to 24 hours. Add an extra 5–10 minutes to the bake time if chilled straight from the fridge. Reheat leftovers at 350°F until warmed through.

Can I double the recipe?

Sure thing. Use two 9×13 pans or one larger pan; cooking time may increase by 10–15 minutes. Keep an eye on the top so it doesn’t over-brown — tent with foil if needed.

Can I substitute butter with oil?

Technically yes, but you’ll miss that buttery magic. Use ¾ the amount of oil.

How do I know it’s done?

Look for bubbling sauce at the edges, a golden-brown top, and slightly crisp edges. If you use a thermometer, the chicken should register 165°F and the casserole should feel set when you jiggle the dish.

What if I don’t have ingredient X?

No panic — swap mushrooms for zucchini or extra onions, use Greek yogurt for sour cream, or sub shredded mozzarella for cheddar. Small swaps change flavor but keep the heart of the dish intact.

How I Like to Serve It

I serve this with a crisp green salad and a lemon vinaigrette to cut the richness, or with roasted carrots for a cozy family meal. It fits weeknight dinners, potlucks, or lazy Sunday lunches. Pair it with a chilled white wine or an easy iced tea — either one balances the creamy, savory flavors beautifully.

Notes

• Store leftovers covered in the fridge up to 4 days. Reheat at 350°F until warmed through, or microwave single portions.
• Ensure chicken reaches a safe internal temp of 165°F whenever you reheat or bake to freshness.

Final Thoughts

Closing: Now go impress someone — or just yourself — with your homemade masterpiece!