A chicken broccoli cheddar pasta casserole brings tender chicken, broccoli, and cheesy pasta together in one easy dinner. See how to make it at home!!

Golden cheddar bubbling around tender pasta, juicy pieces of chicken, and broccoli tucked beneath buttery lemon crumbs make this chicken broccoli cheddar pasta casserole the sort of dinner you want to scoop straight from its baking dish!

What Makes This Casserole So Delicious?

Think of tender pasta shells catching pockets of silky cheddar sauce, with enough chicken and broccoli that every spoonful feels like a complete dinner.

Butter-softened onion and garlic give sauce a savory foundation, while a small amount of paprika adds warmth.

On top, lightly toasted panko brings an airy crunch, and lemon zest adds a fresh aroma that lifts all that rich cheese.

Ingredients

For the Pasta, Chicken, and Broccoli

• 12 ounces / 340 g dry medium pasta shells: Their curves catch cheese sauce beautifully. Short penne or rotini also work; use the same dry weight and follow their package timing as a starting point.
• 1 pound / 450 g fresh broccoli florets: About 5 loosely packed cups, cut into pieces around 1 inch across. Slice any attached stems thinly so they become tender at a similar pace.
• 3 cups / about 450 g cooked chicken: Remove skin and bones, then cut into roughly ¾-inch pieces or shred into chunky strips. Rotisserie chicken, cooked breast, or cooked thigh meat all work.
• Salt for pasta water.
• A little butter for greasing your baking dish.

For the Cheddar Sauce

• 3 tablespoons / 42 g unsalted butter.
• 1 small yellow onion, about 120 g, finely diced: Small pieces soften evenly and blend into sauce.
• 3 garlic cloves, finely minced.
• ¼ cup / 30 g all-purpose flour: Spoon into your measuring cup and level it, rather than packing it down.
• 3 cups / 720 ml whole milk: Whole milk gives sauce a fuller texture. Have an additional ¼ cup available only if you need to loosen sauce before baking.
• 1 cup / 240 ml low-sodium chicken broth.
• 12 ounces / 340 g regular sharp cheddar, freshly grated and divided: Use about 2½ cups / 285 g in sauce and reserve ½ cup / 55 g for topping. Weight is most reliable because grated cheese can pack differently.
• 2 teaspoons Dijon mustard.
• ½ teaspoon sweet paprika: Use sweet rather than hot paprika for a gentle flavor.
• ½ teaspoon freshly ground black pepper.
• ¼ to ½ teaspoon fine salt, to taste: Start with less if your chicken is well seasoned.

For the Crisp Lemon Crumbs

• ¾ cup / about 45 g plain panko breadcrumbs.
• 2 tablespoons / 28 g unsalted butter.
• 1 teaspoon finely grated lemon zest: Grate only yellow skin, leaving bitter white pith behind.
• 2 tablespoons chopped flat-leaf parsley, optional, for serving.

Servings: 8 main-dish portions

How to Make Chicken Broccoli Cheddar Pasta Casserole

Set an oven rack in the middle and preheat to 375°F / 190°C, or 350°F / 175°C if using convection. Lightly butter your deep baking dish, making sure its corners are coated.

Put a large pot of water on to boil, then finish chopping broccoli, dicing chicken, and grating cheddar before you start sauce. Keep your reserved topping cheese in a separate small bowl, because it is surprisingly easy to stir every last shred into sauce when cheese is involved!

Melt 2 tablespoons butter in a large, deep skillet over medium heat, add panko, and stir for 3 to 4 minutes, until crumbs turn pale gold and smell lightly toasted.

Keep them moving, especially around the edges of your skillet, and stop before they become dark brown because they still have oven time ahead.

Transfer crumbs to a bowl, stir in lemon zest, and set aside. This short toast helps you get an evenly crisp topping without having to keep baking just to brown a few stubborn pale patches.
Return that skillet to medium heat and add 3 tablespoons butter and finely diced onion. Cook for 5 to 7 minutes, stirring occasionally, until onion looks translucent and feels soft when pressed with a spoon.

If its edges begin browning quickly, lower heat a little; you want a mellow onion flavor throughout sauce. Stir in garlic for about 30 seconds, just until you can smell it, then sprinkle in flour and stir constantly for 1½ to 2 minutes.

You should have a pale, bubbling paste coating onion, with no dry flour sitting in little corners.

Pour in about 1 cup milk gradually while whisking, taking time to work out lumps before adding remaining milk and chicken broth. Scrape along the bottom and sides, where flour can collect, and bring sauce to a gentle simmer over medium heat.

This usually takes 5 to 7 minutes, depending on how cold your milk was. Once you see small, lazy bubbles, reduce heat and simmer for another 2 to 3 minutes, stirring often, until sauce lightly coats a spoon but still pours easily.

It should be looser than finished macaroni and cheese sauce because cheddar and pasta will both thicken it.

While sauce heats, salt your boiling pasta water and add shells, stirring promptly so they separate. Plan to drain them 2 minutes before the package’s stated al dente time; if that time is 10 minutes, aim for about 8 minutes here.

Add broccoli for only the final 90 seconds of that shortened cooking time, pressing florets into water so they heat evenly. Taste a shell before draining: its outside should be flexible, with a noticeably firm center that will finish cooking in sauce.

Broccoli should look bright green and still resist a fork. If managing both pans feels rushed, move your sauce off heat while you drain pasta; a short pause is better than a scorched pan.

Drain pasta and broccoli together in a large colander, shake gently, and let excess water drip away for 1 to 2 minutes. Pay attention to water trapped inside florets, because it can thin your carefully prepared sauce.

Return everything to your empty pasta pot without rinsing, and keep it nearby while you finish sauce. Don’t skip this draining step; a little patience here helps your casserole stay creamy all the way to its last spoonful!

Take your sauce completely off heat and wait about 1 minute, until bubbling stops. Stir in Dijon, paprika, black pepper, and ¼ teaspoon fine salt, then add the 10 ounces / 285 g cheddar allocated to sauce in several handfuls, stirring each addition smooth before adding another.

Gentle residual heat should melt freshly grated cheese; if necessary, return your skillet to its lowest heat briefly while stirring, but do not let cheese sauce boil.

Taste and decide whether it needs remaining ¼ teaspoon salt, remembering that chicken and topping cheese will contribute seasoning too.

Add chicken and cheddar sauce to your pot of pasta and broccoli, then fold gently with a large spoon until everything is coated. Try to keep florets intact rather than stirring so vigorously that broccoli breaks into green specks.

At this point, sauce should slip between pasta pieces and settle into small glossy pools when you stop stirring.

If it clings in thick clumps, fold in extra milk 1 tablespoon at a time, up to ¼ cup, until mixture loosens. This is your last easy opportunity to adjust moisture before baking.

Spoon mixture into your prepared dish and spread it evenly without packing it down. Leave at least ½ inch of space below its rim; if your dish is shallower than expected, put excess into a small buttered oven-safe dish.

Scatter reserved ½ cup cheddar across the surface, followed by toasted lemon crumbs, keeping both layers fairly even so everyone gets some crunch.

Bake uncovered for 25 to 30 minutes, until sauce bubbles around the edges, topping is golden, and an instant-read thermometer inserted into the center registers 165°F / 74°C.

Start checking at 25 minutes, and continue as needed to reach that temperature. If crumbs brown before the center is hot, lay foil loosely over your dish for remaining baking time.

Let your casserole rest uncovered for 10 minutes before serving. Sauce will settle around pasta while staying creamy, and a serving spoon will lift a neater portion instead of sending everything sliding across your plate.

Scatter parsley over the top if using, then serve while crumbs still have their crispness. I would claim a corner portion now if you enjoy those golden, slightly chewy cheese edges; they tend to become very popular once dinner reaches the table!

Small Adjustments That Make a Difference!!

• Choose cheddar with melting in mind. Regular sharp cheddar gives a good balance of flavor and texture. Very mature, crumbly cheddar can be harder to melt smoothly, and bagged shredded cheese varies in how well it blends.
• Grating a block gives you more control, especially when combined with adding cheese off heat.
• Use frozen broccoli carefully. Substitute the same weight of frozen florets, thaw them completely, and drain and blot well. Skip boiling them with pasta, then fold them into sauce with chicken.
• Frozen broccoli is usually blanched before freezing, so expect a softer finished texture than you get with fresh florets.
• Keep chicken fully cooked before it enters your dish. This recipe’s timing is designed for cooked chicken. If starting with raw chicken, cook it separately to 165°F / 74°C, then measure out the cooked amount.
• Keep pieces reasonably small so they distribute evenly without needing extra baking time.
• Watch texture as well as timing. Once your center reaches 165°F / 74°C and pasta is tender, take your casserole out.
• Extra baking can dry chicken and tighten sauce, even when that golden topping makes it tempting to leave everything in a little longer.

Serving Suggestions

• Serve generous spoonfuls with a crunchy salad of romaine, cucumber, and thinly sliced radishes, dressed lightly with lemon and olive oil.
• Crisp vegetables and a tangy dressing give you a fresh bite between mouthfuls of cheddar-coated pasta, and they are easy to prepare while your casserole rests.
• Roasted carrots or green beans also work well if you would prefer another warm vegetable.
• For a larger dinner, add a basket of small garlic toasts, especially if your guests are likely to chase every remaining streak of sauce around their plates.
• Bring your baking dish to the table on a heatproof trivet and use a wide serving spoon so each portion gets creamy pasta underneath and some golden crumbs on top.

With its bubbling cheddar sauce, tender chicken, fork-sized broccoli, and buttery lemon crunch, this chicken broccoli cheddar pasta casserole gives you plenty to look forward to before you even lift a fork.

Keep pasta slightly firm before baking, give sauce enough room to stay creamy, and let those golden crumbs do their work.

Then scoop out a generous portion while dinner is hot, pass the salad, and enjoy every cheesy bite!