Thanksgiving Leftovers Breakfast Casserole
A practical, savory way to use leftover turkey and stuffing. This bake sets up like a strata: stuffing on the bottom, turkey and cheese in the middle, and a seasoned egg custard that binds everything together.
Why You’ll Love It
- Uses real leftovers (no extra cooking required)
- Mix–pour–bake method with clear doneness cues
- Scales up or down easily; make-ahead or bake now
- Protein-rich and satisfying without being heavy
- Flexible: works with sausage, ham, or veggies if you’re low on turkey
Ingredients (what you actually need)
Yield: 12–15 servings (9×13 pan)
- 4 cups leftover turkey stuffing (packed lightly into the cup)
- 2 cups cooked turkey, chopped into ½-inch pieces (dark or white meat)
- 8 ounces Swiss cheese, shredded (about 2 packed cups)
- 12 large eggs (a full dozen)
- 1 (10.5-ounce) can cream of mushroom soup
- ¼ cup whole milk
If your stuffing is very dry, add 2–4 more tablespoons milk or low-sodium chicken broth. - 1 teaspoon poultry seasoning
- 1 teaspoon kosher salt (reduce to ½ teaspoon if your stuffing is salty)
- ½ teaspoon freshly ground black pepper
- Optional garnish: chopped fresh sage, rosemary, or thyme
Helpful tools:
- 9×13 baking dish (ceramic or metal). A ceramic baking dish like this holds heat well: ceramic 9×13 dish
- Large mixing bowl set: stainless mixing bowls
- Whisk (silicone is gentle on bowls): silicone whisk
- Box grater for better-melting cheese: box grater
- Nonstick spray or brush-on oil, and foil: heavy-duty foil
Steps (do this)
- Heat the oven. Preheat to 350°F (175°C). Position a rack in the center. Lightly grease a 9×13 dish.
- Base layer. Distribute the stuffing in an even layer. Press down lightly with your fingertips or the back of a spoon to create a cohesive base without compacting it hard (you want small air pockets so the custard can flow).
- Turkey + cheese. Scatter the chopped turkey evenly. Sprinkle the shredded Swiss over the top.
- Make custard. In a large bowl, whisk eggs until no streaks remain. Whisk in the soup, milk, poultry seasoning, salt, and pepper until smooth. Little bubbles are fine; visible soup clumps are not.
- Pour and settle. Pour the custard slowly over the casserole. Tap the dish firmly on the counter 2–3 times to help the liquid seep down to the stuffing layer.
- Cover and start baking. Lightly oil one side of a foil sheet; cover oiled-side down to prevent sticking. Bake covered for 30 minutes.
- Uncover and finish. Remove foil and bake 30–40 minutes more, until the top is golden and the center registers 165°F on an instant-read thermometer or a knife inserted in the center comes out clean with no liquid egg. The edges will puff slightly and feel springy.
- Rest and serve. Let rest 5–10 minutes to set. Garnish with herbs if using. Cut into 12–15 squares.
Helpful Tips & Substitutions
Getting the texture right
- Stuffing moisture check: Pinch a bit in your palm. If it holds together and feels damp, you’re good. If it crumbles apart, whisk 2–4 tablespoons extra milk/broth into the custard. If it’s very wet, reduce milk to 2 tablespoons.
- Cheese matters: Shred your own cheese for better melt. Swiss is classic with turkey; Gruyère is richer; sharp cheddar brings more bite and browns deeper.
- Even baking: Ceramic pans run slightly slower than metal. If using a light metal pan, start checking doneness at the 55-minute total mark (25 minutes after uncovering).
Flavor add-ins (use up more leftovers)
- Gravy swirl: Spoon ¼–⅓ cup cooled gravy in thin ribbons over the cheese before pouring the custard. It adds savory depth.
- Veggies: Fold 1–1½ cups sautéed mushrooms, onions, spinach, or roasted Brussels sprouts into the turkey layer. If using watery veg (spinach/mushrooms), cook off moisture first.
- Cranberry pop: Sprinkle ¼ cup chopped dried cranberries over the turkey for a sweet-savory contrast.
Protein swaps
- No turkey: Use 12–14 ounces cooked breakfast sausage (browned and drained), diced ham, or rotisserie chicken.
- All-veg: Skip meat; add 2 cups mixed sautéed veg and increase cheese by 2–4 ounces.
Dietary adjustments
- Gluten-free: Use gluten-free stuffing or roasted potatoes (4 packed cups of ½-inch diced, pre-roasted to tender) as the base.
- Dairy-free: Use a dairy-free cream soup (or homemade white sauce with plant milk) and a meltable dairy-free cheese; swap milk with unsweetened almond or oat milk.
- No canned soup: Replace with a quick white sauce: Melt 2 tablespoons butter, whisk in 2 tablespoons flour; cook 1 minute. Whisk in 1 cup chicken broth + ¼ cup milk; simmer till thick; season with ¼ teaspoon onion powder, ¼ teaspoon garlic powder, pinch of nutmeg. Cool 5 minutes before adding to eggs.
Salt control
Leftovers vary. Taste a small piece of stuffing and turkey. If both are seasoned assertively, start with ½ teaspoon kosher salt in the custard; you can finish with flaky salt at the table.
Oven variables
- Convection: Reduce temp to 325°F. Bake covered 25 minutes; uncover and bake 25–35 minutes.
- From cold (assembled overnight): Add 10–15 minutes to the uncovered time and check for 165°F in the center.
Troubleshooting
- Center still loose after time: Cover lightly with foil and continue in 5–8 minute increments until 165°F.
- Top browning too fast: Tent with foil.
- Watery bottom: Stuffing was very wet. Next time, reduce added milk or pre-toast stuffing on a sheet pan at 350°F for 8–10 minutes before assembling.
- Rubbery eggs: Overbaked. Pull as soon as the center hits 165°F and edges are just set.
Serving Ideas
- Spoon warmed cranberry sauce or leftover gravy over each slice for a Thanksgiving echo.
- Add a simple citrus salad (orange/grapefruit segments with a pinch of salt) to cut richness.
- For brunch: serve with a tray of roasted potatoes or a green salad and hot coffee.
- Keep toppings handy in small bowls: chopped herbs, hot sauce, or crispy onions.
Make-Ahead & Storage
Assemble ahead (best for hosts):
- Build the casserole, cover tightly, and refrigerate up to 24 hours. For the cleanest slices, let the chilled casserole sit at room temp 15 minutes before baking.
Bake ahead:
- Bake fully, cool 30 minutes, then chill uncovered until barely warm before covering (prevents steam sogginess). Reheat covered at 325°F for 20–25 minutes.
Freeze options:
- Before baking: Wrap tightly (press plastic wrap to surface, then foil) and freeze up to 2 months. Thaw in the fridge 24 hours; bake as directed, adding 10–15 minutes.
- After baking: Cool completely, cut into squares, wrap individually, and freeze up to 2 months. Reheat wrapped squares at 325°F for 20–25 minutes or microwave 1½–3 minutes (power varies).
Storage & safety:
- Refrigerate leftovers in airtight containers within 2 hours; keep up to 4 days. A lidded 9×13 works well: glass bake-and-store pan.
- Reheat slices to steaming hot throughout (165°F).
Scaling, Pan Sizes & Timing
- Half batch (8×8 or 9×9): Use half of everything (6 eggs, 4 oz cheese). Bake 20 minutes covered + 20–30 minutes uncovered.
- Three-quarters batch (10×10): Reduce ingredients to ¾; timing similar to half batch plus ~5 minutes.
- Two pans: Double the recipe and bake in two 9×13 dishes; rotate pans halfway through for even browning.
- Muffin tin version (great for freezing): Grease a standard 12-cup tin, add stuffing/turkey/cheese, then pour custard to ¾ full. Bake 14–18 minutes at 350°F, or until 165°F. A sturdy muffin pan helps release cleanly: nonstick muffin pan.
Ingredient Notes (small details that matter)
- Turkey size & cut: ½-inch dice gives even distribution and prevents chewy bites. Mix white and dark meat for moisture.
- Poultry seasoning: If you’re out, use ½ teaspoon dried sage + ¼ teaspoon each dried thyme and marjoram.
- Pepper: Freshly ground makes a difference here; 8–10 turns on a standard mill ≈ ½ teaspoon.
- Milk choice: Whole milk gives body without making the custard heavy. Avoid sweetened plant milks.
- Cheese shredding: Use the large holes of a box grater for melt and coverage. Pre-shredded works but melts a bit drier due to anti-caking starches.
Quick Recipe Card (print-friendly)
Thanksgiving Leftovers Breakfast Casserole
- Prep: 10 minutes | Bake: 60–70 minutes | Total: ~75 minutes | Serves: 12–15
- Heat oven to 350°F; grease 9×13.
- Layer 4 c stuffing, 2 c diced turkey, 8 oz shredded Swiss.
- Whisk 12 eggs + 10.5 oz cream of mushroom soup + ¼ c milk + 1 tsp poultry seasoning + 1 tsp kosher salt (or ½ tsp if salty leftovers) + ½ tsp pepper.
- Pour over; tap pan.
- Cover with oiled foil; bake 30 min.
- Uncover; bake 30–40 min until golden and center hits 165°F and a knife comes out clean.
- Rest 5–10 min; garnish and serve.
This is a technique more than a single recipe: a flavorful base (stuffing), bite-size protein (turkey), meltable cheese, and a well-seasoned egg custard. Adjust moisture based on your stuffing, pull at 165°F, and you’ll get clean slices with a tender, custardy center every time. If you need a reliable thermometer, this style is accurate and quick: instant-read thermometer.