Leftover Turkey Breakfast Casserole

Leftover Turkey Breakfast Casserole is a golden, puffed bake of crusty bread cubes, chopped turkey, sweet peppers, spinach and sharp cheddar held together by a savory sage and thyme custard. The top bakes crisp and cheesy while the middle stays soft and custardy, a little like the best part of stuffing meeting a fluffy omelet. It is a smart, satisfying way to feed a house full of holiday guests the morning after Thanksgiving, and a welcome change from yet another turkey sandwich.

Allow about 1 hour 15 minutes, plus soaking time: 20 minutes of prep and 55 minutes of cooking, almost all of it hands-off in the oven. It is an easy recipe, and the one step worth slowing down for is the soak; giving the bread at least 30 minutes, or overnight, to drink up the custard is what keeps the casserole moist instead of dry and patchy. Serve it for a post-holiday brunch, a lazy weekend breakfast or breakfast-for-dinner.

What is Leftover Turkey Breakfast Casserole?

A leftover turkey breakfast casserole is a strata-style bake, meaning cubes of bread are layered with fillings and soaked in an egg and milk custard before baking. Here the filling is cooked turkey, sautéed onion and bell pepper, spinach and plenty of cheese, seasoned with sage and thyme for a gentle Thanksgiving flavor. As it bakes, the custard sets around the bread while the exposed cubes turn crisp, giving you soft and crunchy textures in every bite. It is usually served warm in squares for breakfast or brunch, often with a spoonful of cranberry sauce on the side.

Reasons to Try Leftover Turkey Breakfast Casserole

• Uses up leftovers — Three cups of cooked turkey and a few slices of stale bread turn into breakfast for eight.
• Make it the night before — Assembling it ahead lets the bread soak overnight, so the morning job is simply turning on the oven.
• Feeds a crowd — One 9×13-inch dish cuts into 8 generous squares, ideal when the house is still full of guests.
• Protein-packed start — Eggs, turkey and cheese add up to roughly 35 grams of protein per serving.
• Flexible fillings — Swap the vegetables, cheese or even the bread for leftover stuffing, and the method stays the same.
• Holiday flavor, new format — Sage, thyme and a side of cranberry sauce echo the feast without tasting like a repeat.

Ingredients Needed to Make Leftover Turkey Breakfast Casserole

This makes one 9×13-inch casserole, about 8 servings.

For the Base

• Day-old crusty bread (6 cups, 1-inch cubes, about 10 oz) — Sturdy, slightly dry bread such as sourdough or a French loaf soaks up custard without turning mushy.
• Unsalted butter (1 tbsp, softened) — Greases the dish so the edges brown and release easily.

Turkey and Vegetables

• Cooked turkey (3 cups, diced) — White and dark meat both work; dark meat stays especially juicy.
• Unsalted butter (1 tbsp) — Softens the vegetables and adds richness.
• Yellow onion (1 medium, diced) — Cooked until sweet, it gives the custard a savory backbone.
• Red bell pepper (1, diced) — Adds color and gentle sweetness.
• Baby spinach (2 cups, roughly chopped) — Wilts into the filling and brings a fresh, green note.

Egg Custard

• Large eggs (10) — The custard sets around the bread as it bakes.
• Whole milk (2 cups) — Keeps the custard tender; half-and-half makes it richer.
• Dijon mustard (1 tsp) — Sharpens the cheese flavor without tasting of mustard.
• Dried sage (1/2 tsp) — Gives the casserole a gentle, stuffing-like aroma.
• Dried thyme (1/2 tsp) — Earthy and warm, it pairs naturally with turkey.
• Kosher salt (1 tsp) — Seasons the bread and eggs evenly.
• Black pepper (1/2 tsp) — Freshly ground for mild heat.

Cheese and Toppings

• Sharp cheddar (1 1/2 cups shredded, divided) — Melts into the filling and browns on top.
• Gruyère (1/2 cup shredded) — Adds a nutty depth; Swiss is a good swap.
• Green onions (2, sliced) — Fresh, mild bite scattered over the finished casserole.
• Cranberry sauce (for serving, optional) — A sweet-tart spoonful on the side ties it back to the holiday.

Equipment Needed

• 9×13-inch baking dish — Gives enough surface for a crisp, golden top.
• Large skillet — Softens the onion and pepper before they go into the casserole.
• Mixing bowl — Whisking the custard in a big bowl makes it easy to pour evenly.
• Aluminum foil — Covers the dish for part of the bake so the top does not over-brown before the center sets.
• Instant-read thermometer — Confirms the center reaches 165°F (74°C), safe for both the eggs and the reheated turkey.

Instructions to Prepare Leftover Turkey Breakfast Casserole

• Prep the dish and bread — Butter a 9×13-inch baking dish and spread half the bread cubes in an even layer. If your bread is fresh, toast the cubes at 300°F (150°C) for 10 minutes first so they hold their shape.
• Cook the vegetables — Melt the butter in a large skillet over medium heat and cook the onion and bell pepper for 6 to 7 minutes until soft. Add the spinach and stir for 1 minute until just wilted, then cool slightly.
• Layer the casserole — Scatter half the turkey, half the vegetables and 3/4 cup cheddar over the bread. Repeat with the remaining bread, turkey and vegetables, then sprinkle with the Gruyère.
• Whisk the custard — Beat the eggs, milk, Dijon, sage, thyme, salt and pepper until smooth, then pour evenly over the casserole.
• Let it soak — Press the bread down gently so every piece is moistened. Cover and refrigerate for at least 30 minutes or up to 24 hours.
• Bake until set — Heat the oven to 350°F (175°C) and let the dish stand at room temperature while it heats. Top with the remaining cheddar, cover with foil and bake 25 minutes, then uncover and bake 25 to 30 minutes more, until puffed, golden and the center reads 165°F (74°C).
• Rest and serve — Rest 10 minutes so the custard firms up, then sprinkle with green onions and cut into 8 squares. Serve with cranberry sauce if you like.

What Goes Well With Leftover Turkey Breakfast Casserole Recipe

Bright, fresh sides balance this rich, cheesy bake.

• Fresh fruit salad — Juicy berries, citrus and grapes cut through the rich, cheesy casserole.
• Roasted breakfast potatoes — Crispy, well-seasoned potatoes turn brunch into a heartier spread.
• Arugula salad with lemon — Peppery greens with a sharp vinaigrette keep the plate light and bright.
• Cranberry orange muffins — Sweet-tart muffins echo the cranberry sauce and round out a holiday brunch.
• Sparkling cranberry orange juice — A splash of cranberry juice in fresh orange juice topped with sparkling water makes a festive brunch drink.
• Cinnamon coffee cake — Tender, crumbly coffee cake makes a sweet finish to brunch.

Key Tips for Making Leftover Turkey Breakfast Casserole Recipe

• Stale bread first — Dry bread absorbs the custard like a sponge, while fresh bread turns soggy, so toast it first if needed.
• Cool the vegetables — Hot vegetables start to cook the eggs unevenly, so let them cool for a few minutes before layering.
• Never skip the soak — Thirty minutes is the minimum, and an overnight rest gives the softest, most even texture.
• Room-temperature start — Letting the chilled dish sit while the oven heats helps the center cook through before the edges dry out.
• Foil for the first half — Covering the dish early stops the cheese from burning before the custard sets.
• Check the center — The middle is the last part to set, so insert the thermometer there and look for 165°F (74°C).
• Rest before slicing — Ten minutes out of the oven lets the custard firm up so the squares hold their shape.

Creative Variations of Leftover Turkey Breakfast Casserole Recipe

• Stuffing swap — Replace half the bread with leftover stuffing for an even more Thanksgiving-flavored bake.
• Southwest style — Use pepper jack, add a can of diced green chiles and 1 teaspoon cumin, and serve with salsa and avocado.
• Mushroom and Gruyère — Sauté 8 oz sliced mushrooms with the onion and use all Gruyère for a richer, earthy version.
• Gluten-free version — Gluten-free bread cubes or diced roasted potatoes can replace the regular bread.
• Sweet potato and kale — Swap the pepper and spinach for roasted sweet potato cubes and chopped kale.
• Muffin-tin portions — Divide the mixture among 12 greased muffin cups and bake 25 to 30 minutes, until 165°F (74°C).

Storage Guidelines for Leftover Turkey Breakfast Casserole Recipe

• Refrigerator — Covered tightly, it keeps for up to 3 days; since the turkey is already a leftover, use it promptly.
• Freezer — Wrap individual squares in plastic and foil and freeze for up to 2 months.
• Cooling — Refrigerate within 2 hours of baking, letting it cool slightly first.
• Unbaked make-ahead — The assembled, unbaked casserole can be refrigerated for up to 24 hours before baking.
• Labeling — Date each package so nothing lingers past its safe window.

Reheating Tips for Leftover Turkey Breakfast Casserole Recipe

• Oven — Cover with foil and heat at 350°F (175°C) for 15 to 20 minutes until the center reaches 165°F (74°C).
• Microwave — Heat a square covered at 70 percent power for 1 1/2 to 2 minutes, until 165°F (74°C).
• Air fryer — Warm a square at 325°F (165°C) for 6 to 8 minutes to re-crisp the top, checking for 165°F (74°C).
• From frozen — Thaw overnight in the refrigerator, then reheat in the oven.

Nutrition Value (per serving)

Based on 1 serving out of 8 total servings.

• Calories — 445
• Protein — 35g
• Fat — 22g
• Saturated Fat — 10g
• Carbohydrates — 22g
• Fiber — 2g
• Sugar — 5g
• Sodium — 675mg
• Cholesterol — 305mg

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