Creamy Mushroom Chicken Casserole

Name: Creamy Mushroom Chicken Casserole
Prep time: 25 min
Cook time: 40 min
Total time: 1 h 5 min
Yield: 6 servings
Cuisine: American
Ingredients: 1½ lb (680 g) boneless, skinless chicken breasts, cooked and diced into ¾-inch (2 cm) pieces; 10 oz (280 g) dried egg noodles, cooked until just barely al dente, drained; 1 lb (450 g) cremini mushrooms, cleaned and sliced ¼-inch (6 mm) thick; 4 tablespoon (57 g) unsalted butter, divided: 2 tablespoons for mushrooms, 2 tablespoons for sauce; 2 medium (80 g) shallots, minced; 3 clove (15 g) garlic cloves, minced; 2½ tablespoon (20 g) all-purpose flour; 1 cup (240 ml) low-sodium chicken broth; 1 cup (240 ml) sour cream, at room temperature; 1 tablespoon (15 ml) Dijon mustard; 1½ teaspoon (4 g) fresh thyme, fresh leaves, stripped from stems; to taste kosher salt; to taste freshly ground black pepper; ½ cup (50 g) panko breadcrumbs; ¼ cup (25 g) grated Parmesan cheese, finely grated; 2 tablespoon (28 g) unsalted butter, melted; 2 tablespoon (8 g) fresh flat-leaf parsley, finely chopped, for garnish (optional)

From the MyKitchenBank Kitchen

A comforting baked casserole with tender chicken breast, earthy mushrooms, and egg noodles bound in a silky sour cream sauce infused with thyme. The top is finished with a light breadcrumb topping that crisps up in the oven, making this a complete one-dish dinner that feeds a crowd.

Prep: 25 min
Cook: 40 min
Wait: 10 min
Total: 1 hr 15 min
Makes: One 9×13-inch (23×33 cm) casserole, 6 servings

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Ingredients

6 servings

1½ lb (680 g) boneless, skinless chicken breasts, cooked and diced into ¾-inch (2 cm) pieces
10 oz (280 g) dried egg noodles, cooked until just barely al dente, drained
1 lb (450 g) cremini mushrooms, cleaned and sliced ¼-inch (6 mm) thick
4 tablespoon (57 g) unsalted butter, divided: 2 tablespoons for mushrooms, 2 tablespoons for sauce
2 medium (80 g) shallots, minced
3 clove (15 g) garlic cloves, minced
2½ tablespoon (20 g) all-purpose flour
1 cup (240 ml) low-sodium chicken broth
1 cup (240 ml) sour cream, at room temperature
1 tablespoon (15 ml) Dijon mustard
1½ teaspoon (4 g) fresh thyme, fresh leaves, stripped from stems
to taste kosher salt
to taste freshly ground black pepper
½ cup (50 g) panko breadcrumbs
¼ cup (25 g) grated Parmesan cheese, finely grated
2 tablespoon (28 g) unsalted butter, melted
2 tablespoon (8 g) fresh flat-leaf parsley, finely chopped, for garnish (optional)

Equipment (5)

9×13-inch (23×33 cm) baking dish
Large skillet (12-inch / 30 cm)
Medium saucepan
Colander
Wooden spoon

Steps

Before you start

Preheat the oven to 350°F (175°C)
Cook the egg noodles 1 minute under the package time so they are still slightly firm (they continue cooking in the oven)
Pat the cooked chicken dry before dicing to remove excess moisture

1
Sauté the mushrooms
- Heat 2 tablespoons (28 g) of butter in a large 12-inch (30 cm) skillet over medium-high heat.
- Once foaming, add the sliced mushrooms and cook for 6–8 minutes, stirring occasionally, until they release their moisture and begin to brown at the edges.
- Season with a pinch of salt and pepper, then transfer to a plate.
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Ready when: Mushrooms are golden brown and have released their liquid
Tip: Don't crowd the pan; let the mushrooms brown rather than steam. If your pan is small, work in two batches.
2
Build the sauce base
- In the same skillet, reduce heat to medium and melt the remaining 2 tablespoons (28 g) of butter.
- Add the minced shallots and cook for 2 minutes until softened and translucent, then add the minced garlic and cook for another 30 seconds until fragrant.
- Sprinkle the flour over the shallots and garlic, stirring constantly for 1 minute to create a light roux.
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Ready when: Flour is incorporated and mixture is light golden
Tip: Stir the flour constantly to avoid lumps and ensure it cooks evenly without browning too much.
3
Deglaze and simmer
- Pour in the chicken broth, stirring constantly to dissolve the roux and prevent lumps from forming.
- Bring to a gentle simmer over medium heat and cook for 2–3 minutes until the sauce thickens slightly.
- The sauce should coat the back of a spoon lightly.
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Ready when: Sauce is smooth and lightly thickened, no lumps visible
Tip: If lumps form, pour the sauce through a fine mesh strainer to remove them before continuing.
4
Add sour cream and seasonings
- Remove the skillet from heat and let cool for 1 minute.
- Whisk in the sour cream and Dijon mustard until fully incorporated and smooth.
- Stir in the fresh thyme leaves.
- Taste and adjust with salt and pepper as needed.
- The sauce should be creamy and well-seasoned.
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Ready when: Sour cream is fully blended; sauce is smooth and creamy
Tip: Let the pan cool slightly before adding sour cream to prevent it from curdling. Cold sour cream added to very hot liquid can break.
5
Combine casserole components
- Return the cooked mushrooms to the skillet and stir to combine with the sauce.
- Add the diced cooked chicken and the cooked egg noodles, folding gently until everything is evenly coated with the creamy sauce.
- Pour the entire mixture into a buttered 9×13-inch (23×33 cm) baking dish and spread it evenly.
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Ready when: All components are evenly distributed and coated in sauce
Tip: Fold gently to avoid breaking apart the noodles and chicken. The noodles should remain visible, not mashed.
6
Make the topping
- In a small bowl, combine the panko breadcrumbs, grated Parmesan cheese, and 2 tablespoons (28 g) of melted butter.
- Toss with a fork until the breadcrumbs are evenly moistened and resemble coarse sand.
- Sprinkle this mixture evenly over the casserole.
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Ready when: Breadcrumbs are evenly coated with butter and cheese
Tip: Use melted butter rather than softened butter so it distributes evenly through the breadcrumbs.
7
Bake the casseroleOven 350°F / 175°C
- Place the casserole in a preheated 350°F (175°C) oven and bake uncovered for 35–40 minutes.
- The casserole is done when the filling is hot throughout (it should bubble gently at the edges), and the topping is golden brown and crisp.
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Ready when: Topping is golden brown; filling bubbles at the edges
Tip: If the topping browns too quickly, tent the casserole loosely with aluminum foil and continue baking.
8
Rest and serve
- Remove the casserole from the oven and let it rest for 10 minutes at room temperature.
- This allows the filling to set slightly, making it easier to serve.
- Garnish with fresh chopped parsley if desired.
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Ready when: Casserole has cooled enough to serve without dripping
Tip: This resting period helps the noodles absorb some of the cream sauce, improving texture and making serving cleaner.

Good to know

Tips

Cook the chicken separately before adding to the casserole—poaching in broth for 15–18 minutes keeps it tender and moist, and you can use that cooking liquid as part of your chicken broth.
Don't skip the resting period after baking. It allows the hot cream sauce to thicken slightly, making the casserole easier to scoop and plate.
For extra richness, substitute half of the chicken broth with heavy cream, reducing the amount to ½ cup (120 ml) cream and ½ cup (120 ml) broth.
Brown the mushrooms in two batches if needed. Overcrowding releases steam instead of allowing them to caramelize, which gives the dish deeper flavor.

Make ahead

You can assemble the casserole completely (through step 6) up to 24 hours ahead. Cover and refrigerate. Bake from cold, adding 10–15 minutes to the baking time; check that the filling is bubbling and the topping is golden before removing from the oven.

Storage & reheating

Store leftovers in an airtight container in the refrigerator for up to 4 days. Reheat, covered, in a 325°F (160°C) oven for 20–25 minutes until hot throughout, stirring gently halfway through. The casserole does not freeze well due to the sour cream sauce, which can separate during thawing; it is best enjoyed fresh or refrigerated within 4 days.

Substitutions

sour cream → Greek yogurt (full-fat). Use the same amount. The sauce will be slightly tangier and less rich, but still creamy. Avoid low-fat varieties, which can curdle more easily.
fresh thyme → 1 teaspoon dried thyme or ½ teaspoon dried sage. Dried herbs are more concentrated, so use half the amount. Stir in with the sour cream rather than fresh.
cremini mushrooms → 8 oz (225 g) mushrooms plus 8 oz (225 g) diced bell pepper (any color). The pepper adds sweetness and color, balancing the earthiness of fewer mushrooms.
dried egg noodles → Pappardelle, fettuccine, or wide egg pasta. Use the same weight of any wide egg pasta. Avoid small shapes like elbow or shells, which don't hold the sauce as well.