Quick Recipe Version (TL;DR)
Quick Ingredients
- Cooking spray or 1 tsp butter (for the dish)
- 5 cups broccoli florets (about 1 lb / 450 g)
- 4 cups cooked chicken, diced or shredded (about 1 1/2 lb / 680 g cooked)
- 3 tbsp unsalted butter
- 1/2 cup yellow onion, finely diced
- 2 cloves garlic, minced
- 3 tbsp all-purpose flour
- 1 cup low-sodium chicken broth
- 1 1/2 cups whole milk
- 1 tsp Dijon mustard
- 1/2 tsp paprika
- 1 tsp kosher salt, plus more to taste
- 1/2 tsp black pepper
- 1/2 cup sour cream
- 1 cup shredded sharp cheddar (about 4 oz / 113 g)
- 1/4 cup grated Parmesan (about 1 oz / 28 g)
- 1 cup panko breadcrumbs
- 2 tbsp unsalted butter, melted (for topping)
- 1 tbsp chopped parsley (optional garnish)
Do This
- 1. Heat oven to 375°F (190°C). Grease a 9×13-inch baking dish.
- 2. Blanch broccoli 2 minutes in boiling salted water; drain well.
- 3. Sauté onion in 3 tbsp butter 3–4 minutes; add garlic 30 seconds.
- 4. Whisk in flour 1 minute; whisk in broth then milk; simmer until thickened (3–5 minutes).
- 5. Off heat stir in Dijon, paprika, salt, pepper, sour cream, cheddar, and Parmesan.
- 6. Fold in chicken and broccoli; spread in dish. Mix panko with melted butter and sprinkle on top.
- 7. Bake 25–30 minutes until bubbly and golden; rest 10 minutes before serving.
Why You’ll Love This Recipe
- Dependable and family-friendly: creamy, cozy flavors with tender chicken and broccoli in every bite.
- From-scratch sauce (no canned soup needed): still quick, but fresher and easily adjustable.
- Crunchy topping: buttery panko adds that satisfying contrast to the creamy casserole.
- Great for leftovers: reheats well for lunches and busy weeknights.
Grocery List
- Produce: broccoli florets, yellow onion, garlic, parsley (optional)
- Dairy: unsalted butter, whole milk, sour cream, sharp cheddar cheese, Parmesan cheese
- Pantry: all-purpose flour, low-sodium chicken broth, Dijon mustard, paprika, kosher salt, black pepper, panko breadcrumbs, cooking spray (optional)
Full Ingredients
Casserole Base
- Cooking spray or 1 tsp unsalted butter (to grease the baking dish)
- 5 cups broccoli florets (about 1 lb / 450 g)
- 4 cups cooked chicken, diced or shredded (about 1 1/2 lb / 680 g cooked; rotisserie chicken works well)
Creamy Lightly Cheesy Sauce
- 3 tbsp unsalted butter
- 1/2 cup yellow onion, finely diced
- 2 cloves garlic, minced
- 3 tbsp all-purpose flour
- 1 cup low-sodium chicken broth
- 1 1/2 cups whole milk
- 1 tsp Dijon mustard
- 1/2 tsp paprika
- 1 tsp kosher salt
- 1/2 tsp freshly ground black pepper
- 1/2 cup sour cream
- 1 cup shredded sharp cheddar cheese (about 4 oz / 113 g)
- 1/4 cup grated Parmesan cheese (about 1 oz / 28 g)
Crunchy Topping
- 1 cup panko breadcrumbs
- 2 tbsp unsalted butter, melted
- 2 tbsp grated Parmesan cheese (optional, for extra savory crunch)
- 1 tbsp chopped parsley (optional, for serving)
Step-by-Step Instructions
Step 1: Preheat the oven and prep the baking dish
Arrange a rack in the center of the oven and preheat to 375°F (190°C). Lightly grease a 9×13-inch baking dish with cooking spray or a thin swipe of butter. This helps prevent sticking and makes serving easier.
Step 2: Blanch the broccoli (quickly) for tender-crisp results
Bring a large pot of water to a boil and add a generous pinch of salt. Add the broccoli florets and cook for 2 minutes—you want the color to turn bright green while the broccoli stays crisp.
Drain immediately and run under cold water for a few seconds (or spread on a tray) to stop the cooking. Drain very well. Dry broccoli helps prevent a watery casserole.
Step 3: Cook the onion and garlic
In a large skillet or saucepan over medium heat, melt 3 tbsp unsalted butter. Add the diced onion and cook for 3–4 minutes, stirring occasionally, until softened and translucent.
Add the minced garlic and cook for 30 seconds until fragrant.
Step 4: Build and thicken the creamy sauce
Sprinkle in the 3 tbsp flour and whisk constantly for 1 minute. The mixture will look like a thick paste—this quick cook removes the raw flour taste.
Slowly whisk in the 1 cup chicken broth until smooth, then whisk in the 1 1/2 cups whole milk. Keep whisking as it comes up to a gentle simmer. Cook for 3–5 minutes, whisking often, until the sauce noticeably thickens (it should coat the back of a spoon).
Step 5: Add the flavor boosters and melt in the cheese
Turn off the heat. Whisk in the Dijon mustard, paprika, salt, and black pepper.
Stir in the sour cream until smooth. Add the shredded cheddar and Parmesan and stir until melted and creamy. Taste and adjust seasoning if needed.
Step 6: Combine, assemble, and top
Add the cooked chicken and well-drained broccoli to the sauce. Fold gently until everything is evenly coated.
Pour the mixture into the prepared baking dish and spread into an even layer.
In a small bowl, mix 1 cup panko with 2 tbsp melted butter (and the optional 2 tbsp Parmesan) until the crumbs look evenly moistened. Sprinkle the topping evenly over the casserole.
Step 7: Bake until bubbly and golden, then rest
Bake uncovered at 375°F (190°C) for 25–30 minutes, or until the edges are bubbling and the topping is golden brown.
Let the casserole rest for 10 minutes before serving. This helps it set so you can slice and scoop clean portions. Finish with chopped parsley if you like.
Pro Tips
- Keep it from getting watery: Drain the broccoli very well after blanching. Excess moisture can thin the sauce.
- Use freshly shredded cheese: Pre-shredded cheese often contains anti-caking agents that can make the sauce less smooth.
- Don’t overbake: The chicken is already cooked, so you’re baking just to heat through and brown the topping. Overbaking can dry it out.
- Control the thickness: If the sauce feels too thick before combining, whisk in 2–4 tbsp extra milk. If it feels thin, simmer 1–2 minutes longer.
- Even browning: If the topping isn’t golden by the end, broil for 1–2 minutes (watch closely so it doesn’t burn).
Variations
- Make it heartier: Stir in 2 cups cooked rice or 3 cups cooked pasta (like penne) when combining. If you do, add an extra 1/2 cup milk to keep it creamy.
- Swap the protein: Use 4 cups cooked turkey (great after the holidays) or 1 1/2 lb cooked diced ham.
- Add extra veggies: Mix in 1 cup sautéed mushrooms or 1 cup frozen peas (thawed) for more color and variety.
Storage & Make-Ahead
Refrigerate: Cool completely, then cover and refrigerate for up to 4 days. Reheat portions in the microwave (covered) or reheat the baking dish at 350°F (175°C) for 15–20 minutes until hot.
Make-ahead: Assemble the casserole (including topping), cover tightly, and refrigerate for up to 24 hours. Bake at 375°F (190°C) for 35–45 minutes (it takes longer straight from the fridge). If the top browns too quickly, cover loosely with foil for the last 10–15 minutes.
Freeze: For best texture, freeze before baking without the panko topping. Wrap tightly and freeze up to 3 months. Thaw overnight in the refrigerator, add fresh panko topping, and bake at 375°F (190°C) for 35–45 minutes until bubbly and hot.
Nutrition (per serving)
Approximate (1/6 of recipe): 450 calories, 44 g protein, 23 g fat, 18 g carbohydrates, 2 g fiber, 6 g sugar, 850 mg sodium. Values vary by brand and exact ingredients used.
