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If you want to completely reinvent leftovers, this easy Thanksgiving casserole recipe combining leftover turkey, mashed potatoes, and puff pastry in a savory pie is a great way to do it. Broccoli rounds out the meal, and a simple 10-minute cheese sauce adds a ton of flavor!
The weekend after Thanksgiving is always pretty hectic around here.
On Friday we put up the Christmas decorations, which involves getting them out of storage, sifting through them as we reminisce, and arranging them just-so.
(My mom is the one who makes sure they’re arranged “properly”. She likes to let us all think we’re helping, but as soon as we leave the room she’ll rearrange something if it wasn’t laid out exactly as she likes it laid out. It’s pretty hilarious when we catch her in the act!)
We usually try to whip up a batch or two of our favorite Christmas cookies, and watch one of our favorite holiday specials on TV. And if there’s time (or a bargain that’s just too good to pass up), we’ll brave the mall.
Between all that, there really isn’t much time for cooking. It’s a good thing there are always tons of leftovers from Thanksgiving, but there are only so many nights in a row that I can eat the same turkey dinner. This meal is a fun one to switch things up while still making use of leftovers!
Why You’ll Love This Thanksgiving Leftovers Casserole
- It completely reinvents Thanksgiving leftovers into a whole new dinner. In savory pie form with broccoli, cheese sauce, and flaky, golden puff pastry, you won’t even realize you’re eating leftover Thanksgiving dinner! And bonus, this casserole freezes well so it’s great for meal prep.
- Cheese sauce, yuuum. It only takes about 10 minutes to make, but it adds so much flavor to this dish. And who doesn’t love cheesy goodness, right?!
- It’s a full meal in one dish. One of the things I love most about casseroles is that they’re a full meal with all the components in one dish. Here the meal is complete with leftover turkey for protein and broccoli for a vegetable. If you like, you can serve it along with a green salad on the side to get more veggies in!
- Golden, flaky puff pastry. There’s just something about a flaky crust. It’s buttery and delicious, and also provides great texture for this Thanksgiving leftovers pie. It’s perfect comfort food!
Ingredients
Breaking It Down
Ingredients Explained
In this section I explain the ingredients and give substitution ideas where applicable. For the full recipe (including the ingredient amounts), see the recipe card below.
- Unsalted butter – Here we make a quick homemade cheese sauce (called Mornay sauce in French) that’s thickened with roux (a mixture of butter and flour).
- Onion and garlic – These aromatics lend a ton of flavor to the cheese sauce.
- Flour – To thicken the cheese sauce. You can use regular all-purpose flour or your favorite gluten free all-purpose flour blend.
- Milk – Use whole milk for rich flavor and creamy texture.
- Dijon mustard – Just like when I make homemade macaroni and cheese, I like to add a touch of Dijon to this cheese sauce. It adds a subtle sharpness for balance and helps cut through the cheese’s richness.
- Worcestershire sauce – Worcestershire sauce is another “secret” ingredient in my mac and cheese, so I add a bit to the cheese sauce here. This fermented condiment adds depth and complexity with its umami flavor.
- Smoked sweet paprika – Lends an underlying subtly smoky flavor to the cheese sauce, and helps give it beautiful golden color.
- Salt and black pepper – To season the cheese sauce.
- Sharp white cheddar – Use a good sharp white cheddar here, or go for something like Gruyère.
- Leftover mashed potatoes – Or you can use store-bought mashed potatoes or leftover stuffing.
- Leftover turkey – If you’re making this after Thanksgiving, it’s a great way to help use up some turkey! Or you can use leftover roast chicken or rotisserie chicken.
- Broccoli – You can use leftover steamed broccoli, frozen broccoli (thawed and drained), or blanched broccoli here.
- Puff pastry – Frozen puff pastry is easy and convenient. For this recipe, I use one sheet of puff pastry (half of a 17.3-ounce package). If you prefer, you can use a flaky butter pastry crust instead. (I share my favorite pie dough in my blueberry pie recipe; if you make it, you can make a half batch because this savory pie only has a top crust).
- Egg – Lightly beaten with a splash of water to make the egg wash that gets brushed on top. Egg wash gives this savory turkey pie a rich, golden color and glossy shine.
Step-by-Step Instructions
Here are step-by-step instructions to walk you through making this recipe. For the recipe video, please see the recipe card below.
- Make the cheese sauce. Add the butter to a medium saucepan over medium heat. Stir in the onion and cook until softened, but not browned, about 5 minutes, stirring occasionally. Add the garlic and cook 1 minute more, stirring constantly. Add the flour and cook 1 minute. Whisk in the milk, Dijon, Worcestershire, paprika, salt, and pepper, and bring to a simmer, whisking frequently. Turn off the heat and whisk in the cheese a handful at a time until smooth. (TIP: Let the cheese sauce cool a bit so that the puff pastry isn’t going on top of hot sauce, which may cause it to not rise properly.)
- Assemble the casserole. Spread the mashed potatoes in the bottom of the prepared dish. Spread the chopped turkey evenly on top of the mashed potatoes, and then spread the broccoli evenly on top of the turkey. Top with the cheese sauce, and spread it out evenly as best you can. Unwrap the thawed puff pastry and place it on top of the casserole, tucking the sides down into the dish. Brush a little egg wash on top (there will be extra; don’t try to use it all), and cut a few slits in the top of the puff pastry for the steam to vent.
- Bake the casserole. Bake until the pastry is puffed and golden, about 25 to 30 minutes. Cool slightly before cutting and serving.
Storage Tips
Store leftovers covered in the fridge for up to 4 days.
How to Freeze Turkey Puff Pastry Pie
- Assemble the casserole, but don’t put the puff pastry on top.
- Let the casserole cool to room temperature.
- Wrap the entire casserole well with plastic wrap.
- Freeze it for up to 3 months.
- The night before you want to make this turkey puff pastry pie, put it in the fridge to thaw overnight along with a sheet of puff pastry.
- When you want to bake it, put the puff pastry on top of the thawed casserole and bake as directed.
Variations
- No turkey, no problem. If it’s not right after Thanksgiving and you don’t have a ton of turkey in your fridge, no worries! You can also use leftover roast chicken or rotisserie chicken to make this.
- Swap out the broccoli. I’ve also made this casserole with steamed cauliflower instead of broccoli and it’s every bit as good.
- Use your favorite cheese. Instead of cheddar, you can use anything you like! Try Gouda, Colby, Edam, Swiss, or a combination of cheeses.
My Best Tips For Thanksgiving Casserole with Leftover Turkey and Puff Pastry
- You don’t want soupy mashed potatoes. Then your finished casserole won’t have any structure. If you’re using leftover mashed potatoes, they should stiffen and dry out in the fridge. They should be a bit dry. On the other hand, if your leftover mashed potatoes look too dry and crumbly, you can stir in a splash of milk.
- Make sure your broccoli is crisp-tender. Don’t use raw broccoli because it won’t soften enough while the casserole is in the oven. You can use frozen broccoli (thawed and drained), or blanch broccoli florets. To blanch broccoli florets, bring a pot of water to a boil. Once boiling, salt the water, add the broccoli florets, and boil until crisp-tender, about 1 to 2 minutes. Drain well (or if you want to immediately stop the cooking process, transfer the broccoli from the boiling water to a large bowl of ice water; I don’t bother with this step for this recipe though).
- The cheese sauce will be thick. That’s exactly how we want it! We want the cheese sauce to add flavor, not make the casserole soupy.
Frequently Asked Questions
Yes! Thaw it well, drain it, and pat it dry so it doesn’t make the casserole watery.
Absolutely. Stuffing instead of mashed potatoes is also delicious in this casserole.
Definitely! You can use store-bought pie crust or homemade pie dough.
Nope! If you prefer, you can use 6 to 8 ounces of your favorite shredded cheese instead.
More Delicious Ways to Use Up Thanksgiving Leftovers
- Cranberry Oatmeal Bars
- Grilled Cheese Thanksgiving Leftoveres Sandwich
- Cranberry Cake
- 15-Minute Leftover Turkey Stroganoff
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Leftover Thanksgiving Casserole Recipe (Turkey, Mashed Potato, and Puff Pastry Pie)
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Ingredients
- Butter to grease the dish
- 3 tablespoons unsalted butter
- 1 medium onion diced
- 2 cloves garlic minced
- 3 tablespoons all-purpose flour
- 1 cup milk at room temperature
- 1 teaspoon Dijon mustard
- 1 teaspoon Worcestershire sauce
- 1/4 teaspoon smoked paprika
- 1/4 teaspoon salt
- 1/8 teaspoon black pepper
- 6 ounces sharp cheddar shredded
- 2 cups leftover mashed potatoes or leftover prepared stuffing (see Notes)
- 2 1/2 cups cooked chopped leftover turkey or chicken
- 3 1/2 cups cooked broccoli florets (see Notes)
- 1 sheet frozen puff pastry thawed in the fridge overnight (I used 1/2 of a 17.3 oz package)
- 1 egg lightly beaten with 1 tablespoon water (for egg wash)
Instructions
- Prep. Preheat oven to 400F. Grease an 8 by 8-inch casserole dish with butter.
- Make the cheese sauce. Add the butter to a medium saucepan over medium heat. Stir in the onion and cook until softened, but not browned, about 5 minutes, stirring occasionally. Add the garlic and cook 1 minute more, stirring constantly. Add the flour and cook 1 minute. Whisk in the milk, Dijon, Worcestershire, paprika, salt, and pepper, and bring to a simmer, whisking frequently. Turn off the heat and whisk in the cheese a handful at a time until smooth. (TIP: Let the cheese sauce cool a bit so that the puff pastry isn’t going on top of hot sauce, which may cause it to not rise properly.)
- Assemble the casserole. Spread the mashed potatoes in the bottom of the prepared dish. Spread the chopped turkey evenly on top of the mashed potatoes, and then spread the broccoli evenly on top of the turkey. Top with the cheese sauce, and spread it out evenly as best you can.
- Top with the puff pastry. Unwrap the thawed puff pastry and place it on top of the casserole, tucking the sides down into the dish. Brush a little egg wash on top (there will be extra; don't try to use it all), and cut a few slits in the top of the puff pastry for the steam to vent.
- Bake. Bake until the pastry is puffed and golden, about 25 to 30 minutes. Cool slightly before cutting and serving.
Video
Notes
- Mashed Potatoes: Taste the leftover mashed potatoes and add salt and pepper as necessary. They should be dry, but if they’re very dry and crumbly, stir in a little milk (don’t add too much though; they should not be soupy!). Or if you don’t have leftover mashed potatoes, you can buy mashed potatoes at the grocery store.
- If You Don’t Have Leftover Broccoli: You can use frozen broccoli (thawed, drained, and patted dry). Or you can blanch the broccoli. To do so, you will need 1 pound of raw broccoli (about 4 cups of chopped broccoli florets). To blanch it, bring a pot of water to a rolling boil. Season the water with salt, add the broccoli, and cook until crisp-tender, about 1 1/2 to 2 minutes. Drain the broccoli and set aside to cool.
- Storage: Store leftovers covered in the fridge for up to 4 days.
- Assemble the casserole, but don’t put the puff pastry on top.
- Let the casserole cool to room temperature.
- Wrap the entire casserole well with plastic wrap.
- Freeze it for up to 3 months.
- The night before you want to make this turkey puff pastry pie, put it in the fridge to thaw overnight along with a sheet of puff pastry.
- When you want to bake it, put the puff pastry on top of the thawed casserole and bake as directed.
Nutrition
Nutritional information is automatically calculated and should be used as an approximate.
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This post was first published on An Edible Mosaic on November 17, 2014, and updated on December 1, 2025.
I’m the writer, recipe developer, photographer, and food stylist behind this blog. I love finding the human connection through something we all do every day: eat! Food is a common ground that we can all relate to, and our tables tell a story. It’s my goal to inspire you to get in the kitchen, try something new, and find a favorite you didn’t know you had.
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Leftovers are the best and worst part of Thanksgiving! Best because YUM and worst because they last FOREVER. Love this as a way to make them new again!
I am definitely going to try it!
Don’t tell the Thanksgiving authorities, but I tend to enjoy the re-purposed Thanksgiving leftovers more than the actual feast itself. There’s just so much you can do with all those food items – enter: puff pastry pie. How genius is this thing??? I love the way you think, m’dear!
That story about your Mom ….my Mom is the SAME way! Cracks me up. Sounds like the perfect black Friday to me. Since I have to teach this black Friday and we have family pictures planned….this would make for the perfect dinner
Simply mouthwatering Faith! I love all the flavors!
A wonderful idea! Leftovers are so great and this dish is perfect.
Cheers,
Rosa