Leftover Turkey, Mashed Potato & Gravy Breakfast Casserole 5 ★

55 min | easy

Baked breakfast casserole in a white rectangular dish, topped with fluffy mashed potatoes and melted cheddar browned in spots, sprinkled with herbs on a marble countertop.

Published Oct 5, 2025

Prep Time	Cook Time	Total Time
20 min	35 min	55 min

Rate/Review

Introduction

This leftover turkey, mashed potato, and gravy breakfast casserole turns holiday scraps into a cozy, bake-and-serve morning feast.

It’s packed with tender turkey, creamy potatoes, melted cheddar, and veggies, so every bite tastes like a mini Thanksgiving plate.

Perfect for the morning after a big celebration, it’s a hearty, family-friendly breakfast that clears out the fridge in one go.

Square slice of leftover turkey, mashed potato, and gravy breakfast casserole on a white plate, topped with browned melted cheddar and a few herb leaves; peas and corn peek out at the edges, with a fork beside it.

How to Make Leftover Turkey, Mashed Potato & Gravy Breakfast Casserole

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Preheat oven and prepare baking dish

Preheat your oven to 375°F and lightly grease a 9x13 inch baking dish.
Create the mashed potato base

Spread 2 cups of the leftover mashed potatoes evenly over the bottom of the prepared baking dish.

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Whisk the egg and gravy mixture

In a large bowl, whisk together the eggs, milk, turkey gravy, garlic powder, onion powder, salt, and pepper.
Add turkey, vegetables, and some cheese

Stir in the shredded turkey, frozen mixed vegetables, and half of the shredded cheddar cheese.
Layer the filling over the potatoes

Pour this mixture over the mashed potato base, spreading it into an even layer.

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Top with remaining mashed potatoes

Dollop the remaining 2 cups mashed potatoes over the filling, then gently spread to mostly cover the surface.
Brush with butter and add cheese

Drizzle the melted butter over the top potatoes, then sprinkle on the remaining shredded cheddar cheese.
Bake the casserole

Bake for 30 to 35 minutes, until the casserole is puffed, the cheese is melted, and the center looks set.

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Rest and serve

Let the casserole rest for 10 minutes before slicing, so the layers firm up and serving is easier.

Overhead view of a baked breakfast casserole in a white rectangular dish, topped with swirls of mashed potatoes, melted cheddar cheese browned in spots, and a sprinkle of green herbs.

Substitutions

Leftover turkey -> Cooked chicken or ham: Cooked shredded chicken or diced ham both stand in easily for turkey and keep the casserole hearty and satisfying.
Cheddar cheese -> Pepper jack or mozzarella: Pepper jack adds a gentle kick and extra flavor, while mozzarella melts very stretchy and gives a milder, kid-friendly taste.
Frozen mixed vegetables -> Cooked broccoli, spinach, or roasted vegetables: Chopped cooked broccoli, wilted spinach, or leftover roasted vegetables all work well and bring different textures and flavors.

Close-up of a square slice of turkey, mashed potato, and egg breakfast casserole on a white plate, topped with melted cheddar and browned edges; peas, carrots, and corn are visible in the layers with a small puddle of gravy beside it, and the rest of the casserole sits blurred in a white baking dish in the background.

Tips

Warm the mashed potatoes slightly: Cold mashed potatoes are hard to spread, so warm them gently in the microwave until just soft and pliable.
Use room-temperature eggs: Room-temperature eggs blend more smoothly with the gravy and milk, which helps the custard bake evenly and set nicely.
Check seasoning before baking: Gravy and mashed potatoes can be salty, so taste the egg mixture and adjust salt or pepper before baking.
Make it the night before: Assemble the casserole, cover, and refrigerate overnight if you like an easy morning. Add 5 to 10 extra minutes of baking time since it starts cold from the fridge.
Let it rest before cutting: Resting time lets the eggs finish setting, so your slices cut cleanly and do not slump apart.

Nutrition Facts ^*

Energy	352	kcal
Protein	23	g
Total Fat	17	g
Carbohydrates	28	g
Dietary Fiber	3	g

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

FAQ

Can I assemble this casserole ahead of time?: Yes, you can assemble it up to 24 hours ahead. Cover tightly and refrigerate. Bake straight from the fridge, adding about 10 minutes so the center cooks through safely.
Why is my casserole watery or loose?: This can happen if the mashed potatoes or vegetables release extra moisture, or if the eggs are underbaked. Bake until the center looks set and barely jiggles, then let it rest before slicing.
Can I freeze leftovers?: Yes, this casserole freezes well in individual portions wrapped tightly and stored in a freezer-safe container. Reheat from frozen in a 350°F oven until hot in the center, about 25 minutes or longer.
Can I use fresh vegetables instead of frozen mixed vegetables?: Yes, you can use small-diced fresh vegetables like carrots, bell pepper, or broccoli florets instead. Lightly steam or sauté firm vegetables first so they become tender by the time the eggs set.
How do I know when the eggs are fully cooked?: The casserole is done when the center no longer looks wet and a knife comes out mostly clean. For extra accuracy, check that the middle reads at least 160°F on an instant-read thermometer.

Serving Suggestions

This cozy casserole makes an easy weekend brunch with a simple green salad or a bowl of fresh fruit.

For a fun twist, add crispy bacon on top after baking or serve with hot sauce on the side.

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.

Reviews

Rated 5 ★ (out of 5) based on 3 reviews.

Post your review and pictures below! ⬇︎

Christine, Ottawa, Canada: Turned out super cozy and satisfying, with the gravy making everything extra rich and the cheese getting perfectly melty on top. Small note: thaw and pat the frozen veggies dry so it doesn’t get watery. — 5 ★

Eunice: So glad it worked out, Christine! Great tip on thawing and patting the veggies dry, that really helps keep the casserole from getting watery.
Karen, Pittsburgh, PA: I made this and it was a huge hit. Used leftover rotisserie chicken instead of turkey since that is what I had. Swapped frozen mixed veggies for chopped broccoli and carrots as well. Served with hot sauce and a simple fruit salad. Will make again. — 5 ★

Eunice: Love hearing that, Karen! Rotisserie chicken and the broccoli-carrot swap are both great in this casserole, and hot sauce on top is always a good call.
taylor__, Pittsburgh: Turned out fantastic and such a smart way to use up leftovers, I added a little hot sauce at serving and it was perfect for brunch. — 5 ★

Eunice: Love hearing it worked out for brunch!