It was a Tuesday night and I genuinely didn’t want to move. I’d had the whole mental picture: sitting at a table in some dimly lit Italian restaurant, a bowl of creamy fettuccine alfredo in front of me, the kind that coats the back of a spoon. But going out meant pants, keys, parking, a wait, a bill. So I stood in my kitchen in socks, looked at what I had, and decided I’d just make something better at home. That decision turned into this chicken alfredo casserole. All the creamy, garlicky, cheesy satisfaction of restaurant alfredo, but baked into a dish that feeds a crowd and reheats beautifully the next day. Not going out was the right call.

What You’ll Need

• 1½ lbs boneless skinless chicken thighs, cut into chunks
• 2½ cups low-sodium chicken broth
• 6 garlic cloves (4 crushed, 2 chopped)
• 3 wide strips lemon zest
• 1 tablespoon lemon juice
• 2 rosemary sprigs
• 2 bay leaves
• 1 lb penne pasta
• 6 cups broccoli florets (about 1 lb)
• 4 tablespoons unsalted butter, plus more for greasing
• 4 tablespoons all-purpose flour
• 2 cups heavy cream
• 1¼ cups grated Parmesan cheese, divided
• 2 cups shredded low-moisture mozzarella
• ¼ cup fresh parsley, chopped
• Kosher salt and black pepper to taste

How to Make It

1. Preheat and prep.

Start by preheating your oven to 400°F and buttering your baking dish generously. Get a large pot of salted water going on the stove at the same time, because you’ll want it boiling by the time the chicken is done.

2. Poach the chicken.

For the chicken, add the chunks to a Dutch oven along with the broth, 4 crushed garlic cloves, the lemon zest strips, rosemary sprigs, and bay leaves. Poaching the chicken in seasoned broth instead of just boiling it plain is the move here — it builds flavor from the start, and that poaching liquid becomes the base of your alfredo sauce later, which means nothing gets wasted. Bring it up to a gentle simmer over medium-low heat, partially cover the pot, and let it go for 20 to 22 minutes until the chicken is totally tender. The chicken shouldn’t be at a rolling boil — you want a low, steady simmer so the meat stays juicy.

Once the chicken’s done, strain it and set aside about 2 cups of that cooking liquid. Don’t throw it away. That’s your flavor base. Let the chicken cool for a few minutes, then shred it into small pieces using two forks. It should pull apart easily. Wipe out the Dutch oven so it’s ready for the sauce.

3. Cook the pasta and broccoli.

While the chicken is cooling, cook your penne in the boiling salted water until it’s just al dente — still slightly firm in the center. In the last 2 minutes of cooking, throw in the broccoli florets. They’ll soften just enough without going mushy. Drain everything, rinse with cold water to stop the cooking, and let it drain really well in the colander. You don’t want extra water thinning out your sauce later.

4. Make the alfredo sauce.

Now for the sauce, and this is where it all comes together. Melt the butter in the cleaned Dutch oven over medium heat. Add the 2 chopped garlic cloves and cook them for about 30 seconds, just until they’re fragrant and sizzling. Don’t let them brown — burned garlic will make the whole sauce bitter. Sprinkle in the flour and stir it constantly for 1 to 2 minutes until it smells slightly nutty and the raw flour smell is gone. This little roux is what thickens your sauce and gives it body.

Whisk in the reserved chicken cooking liquid and the heavy cream. Keep whisking as you pour so no lumps form. Season with salt and black pepper, then let it simmer for 3 to 4 minutes, stirring regularly, until it thickens up to a creamy, coat-the-spoon consistency. Pull it off the heat and stir in 1 cup of the Parmesan, the chopped parsley, and the tablespoon of lemon juice. The lemon cuts through the richness just enough that it doesn’t feel heavy. I actually tasted it at this point and stood there eating spoonfuls straight from the pot. That’s how you know the sauce is right.

5. Combine and top with cheese.

Add the shredded chicken, the drained pasta, and the broccoli directly into the Dutch oven with the sauce and stir it all together until everything is well coated. The key is making sure every piece of pasta is touching sauce — dig in from the bottom when you stir to get the pasta that sinks down. Transfer the whole mixture into your buttered baking dish and spread it out evenly. Top it with the remaining ¼ cup of Parmesan and all 2 cups of shredded mozzarella.

6. Bake and rest.

Bake uncovered at 400°F for 25 minutes. You’re looking for the top to be golden and bubbly, with some crispy cheese edges around the sides. If it’s browning too fast before the middle is hot, tent it loosely with foil. Pull it out and let it rest for 5 minutes before you dig in. That rest time matters more than it seems — the sauce tightens up a little and the whole thing holds together much better when you serve it.

Quick Tips

• Undercook the pasta. Pull it out 1 to 2 minutes before the package says done. It finishes cooking in the oven and if it goes in fully cooked it’ll come out mushy.
• Rotisserie chicken works great here. Skip the poaching step and use about 4 cups of shredded rotisserie chicken. Just use store-bought chicken broth for the sauce instead.
• Don’t skip the resting time. Five minutes out of the oven is enough for the casserole to set up and slice cleanly rather than falling apart on the plate.