Leftover Turkey Sweet Potato and Apple Casserole

1 h 5 min | intermediate | high-protein

Overhead view of a white rectangular baking dish filled with turkey, sweet potato, and apple casserole, topped with melted cheese, browned bread cubes, and scattered herbs on a marble countertop with a folded kitchen towel beside it.

Published Sep 1, 2025

Prep Time	Cook Time	Total Time
25 min	40 min	1 h 5 min

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Introduction

This leftover turkey, sweet potato, and apple casserole turns holiday extras into a cozy, family-friendly dinner everyone will love.

Sweet potatoes and apples bring natural sweetness that pairs beautifully with tender turkey and a creamy, herb-scented sauce.

A layer of melted Gruyère on top adds rich, nutty flavor and a golden, bubbly crust you will crave all season.

Serving of turkey, sweet potato, and apple casserole on a white plate, showing shredded turkey and orange sweet potato chunks in a creamy sauce with melted Gruyère and green herb garnish; baking dish is blurred in the background.

How to Make Leftover Turkey Sweet Potato and Apple Casserole

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Prep the oven and sweet potatoes

Preheat your oven to 375°F and lightly grease a 9x13 inch baking dish.
Place the cubed sweet potatoes in a saucepan, cover with cold water, and add a generous pinch of salt.
Bring to a boil, then simmer 8 to 10 minutes, just until the pieces are barely fork tender.
Drain very well and set the sweet potatoes aside to steam dry in the colander.
Make the creamy maple herb sauce

In a large skillet over medium heat, melt the butter, then add the diced onion.
Cook, stirring often, until the onion is soft and translucent, about 4 to 5 minutes.
Sprinkle the flour over the onions and cook, stirring, for 1 to 2 minutes to remove the raw flour taste.
Slowly whisk in the chicken broth while stirring constantly to avoid lumps.
Stir in the chicken bouillon, dried sage, thyme, salt, and black pepper.
Simmer for 3 to 4 minutes, then pour in the heavy cream and maple syrup, and stir until smooth.
Taste and adjust the seasoning if needed, remembering the cheese and turkey will also add salt.

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Combine the turkey, apples, and sweet potatoes

In a large mixing bowl, add the shredded turkey, drained sweet potatoes, and diced apples.
Pour the warm sauce over the mixture and toss gently until everything is evenly coated.
Assemble and bake the casserole

Transfer the filling to the prepared baking dish and spread it into an even layer.
Sprinkle the shredded Gruyère evenly over the top.
Bake for 25 to 30 minutes, until the casserole is bubbling and the cheese is melted and lightly golden.
If you like extra color, broil for 1 to 2 minutes, watching closely so the cheese does not burn.
Rest, garnish, and serve

Let the casserole rest for 10 minutes so the sauce can thicken slightly and the pieces hold together.
Serve warm, with a simple green salad or roasted Brussels sprouts on the side if you like.

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Overhead view of baked turkey, sweet potato, and apple casserole in a white handled baking dish, topped with melted Gruyère, browned edges, and scattered herbs.

Substitutions

Gruyère cheese -> shredded Swiss or white sharp cheddar: Use equal amount of shredded Swiss or white sharp cheddar for a similar melt and nutty richness. Cheddar adds a slightly bolder flavor, while Swiss stays milder but still creamy.
Heavy cream -> half-and-half plus butter: Replace the heavy cream with 1/3 cup half-and-half plus 1 tablespoon melted butter for each 1/2 cup cream. The sauce will be a bit lighter but still rich and silky.
Sweet potatoes -> butternut squash cubes: Swap the sweet potatoes for equal cups of peeled, cubed butternut squash for a slightly earthier, less sweet base. The casserole stays colorful and cozy, with a texture that turns very tender in the oven.

Tips

Dry the sweet potatoes well: Let the drained sweet potatoes steam off extra moisture, or the sauce can feel thin and watery after baking.
Cut everything about the same size: Aim for 1/2 inch pieces so the apples, onions, and sweet potatoes cook evenly and the casserole feels balanced.
Use room temperature turkey: If your turkey is very cold, let it sit out while you prep so it warms slightly before baking.
Grate your own cheese: Freshly grated Gruyère melts more smoothly than pre-shredded, which often contains starches that can make the sauce grainy.
Let leftovers cool before refrigerating: Cool the casserole to just warm, then cover and refrigerate so condensation does not make the topping soggy.

Nutrition Facts ^*

Energy	365	kcal
Protein	26	g
Total Fat	18	g
Carbohydrates	25	g
Dietary Fiber	3	g

^* Approximate, per serving.
Data source: USDA FoodData Central.

FAQ

Can I make this casserole ahead of time?: Yes, you can assemble the casserole through adding the cheese, then cover and refrigerate for up to 24 hours. Add 5 to 10 extra minutes of baking time since it will start out cold.
How do I keep the sauce from turning lumpy?: Whisk the broth in slowly while stirring constantly, and make sure the flour cooks in the butter for a minute first. If you still get small lumps, you can strain the sauce or blend it briefly with an immersion blender.
Can I use chicken instead of turkey?: Absolutely, cooked shredded chicken works just as well as turkey here. Rotisserie chicken makes this especially easy on a busy night.
Does this casserole freeze well?: Yes, bake it, cool completely, then wrap tightly and freeze for up to two months. Thaw overnight in the refrigerator, then reheat covered at 350°F until hot in the center.

Serving Suggestions

This cozy casserole pairs beautifully with a crisp green salad, cider, or a glass of light Chardonnay.

For extra flavor, scatter toasted pecans on top after baking or stir in a handful of dried cranberries.

You can also finish each serving with a small drizzle of maple syrup to bring out the apples' sweetness.

Recipe by Eunice.
“I learned to cook by standing in my grandma’s kitchen, watching her turn simple ingredients into meals that fed our entire family. That’s where it started. Today, I create recipes for real life, real kitchens, and anyone who wants good food without overthinking it.” Read more.