Ring in the new year with a casserole that lets you sleep in and still serve a show-stopping brunch. This layered masterpiece of sourdough bread, maple-kissed sausage, roasted peppers, and triple-cheese custard is designed to be assembled the night before, so all you do on January 1st is slide it into the oven and watch your guests melt into their seats.

I started making this casserole back in 2014 when my best friend begged me to host a low-key New Year’s brunch—low-key being the operative word after we’d stayed up dancing until 3 a.m. I wanted something that felt celebratory (hello, bubbly mimosas) but required zero morning brain power. One bite in and the entire table declared it “the official breakfast of January first.” Since then, the recipe has traveled to ski cabins, beach rentals, and countless neighborhood potlucks. It’s forgiving, adaptable, and—best part—tastes like you hired a caterer while you were still in your pajamas.

Why This Recipe Works

Make-ahead magic: Assemble up to 24 hours in advance; the bread soaks up every drop of savory custard so each slice holds together.
Feeds a crowd: One 9×13 pan yields 12 hearty slices—perfect for buffet-style serving.
Balanced flavors: Sweet Italian sausage, smoky paprika, and a whisper of maple create sweet-savory harmony.
Texture contrast: Crispy baked cheddar lid, custard-soaked middle, and a base that caramelizes against the pan.
Customizable: Swap the sausage for mushrooms, use gluten-free bread, or go dairy-free with nut milks and vegan cheese.
Zero morning stress: Pop it into a cold oven, set the timer, and go pour the coffee—no preheat required.

Ingredients You'll Need

Great casseroles start with great building blocks. Here’s what to look for—and how to substitute smartly:

Sourdough Loaf: A sturdy country-style sourdough (day-old is ideal) holds its shape after the overnight soak. Avoid soft sandwich bread; it turns gummy. Gluten-free? Pick a crusty GF artisan loaf and cube, then dry 15 min in a 300 °F oven.

Sweet Italian Sausage: I use the bulk variety so there’s no casing to remove. The gentle fennel and mild heat pair beautifully with maple. Turkey or chicken sausage works, but add 1 Tbsp olive oil to compensate for lost fat.

Red & Orange Bell Peppers: Their natural sugars intensify when roasted, lending a jammy sweetness. Out of season? Use drained jarred roasted peppers or even frozen fajita mix—just pat dry.

Spinach: Fresh wilts in seconds and keeps color vibrant. If you only have frozen, thaw and squeeze bone-dry or excess water will thin the custard.

Triple Cheese Combo: Sharp white cheddar for bite, fontina for melt, and a whisper of Parmesan for umami. Buy blocks and shred yourself; pre-shredded cellulose can make the custard grainy.

Eggs & Half-and-Half: The 1:2 ratio creates a custard that slices cleanly yet still jiggles. Swap half-and-half with equal parts whole milk and heavy cream, or use 1¾ cups oat milk + ¼ cup melted butter for dairy-light.

Maple Syrup & Dijon: These are the “secret” background singers—maple highlights the sausage’s sweetness, while Dijon adds subtle acidity to keep each bite from feeling heavy.

Smoked Paprika & Nutmeg: Smoked paprika brings campfire notes; nutmeg whispers holiday comfort. Both are optional but highly recommended.

How to Make New Year's Day Brunch Casserole With Make Ahead Ease

Prep the pan & bread

Butter a 9×13-inch glass or ceramic baking dish. Cube sourdough into 1-inch pieces (roughly 12 cups). Spread across two rimmed trays; let sit uncovered 2 hours to stale slightly. If you’re in a rush, bake at 300 °F for 15 minutes, turning once.

Brown the sausage

Heat a large skillet over medium. Add sausage, breaking into marble-size pieces. Cook 6–7 min until just golden. Transfer to a plate, leaving drippings.

Roast the peppers & aromatics

In the same skillet, add diced peppers and onion. Sauté 4 min until edges blister. Stir in garlic, smoked paprika, salt, and pepper; cook 30 seconds. Fold in spinach until wilted. Remove from heat and mix with sausage.

Build the layers

Scatter half the bread cubes in the buttered dish. Spoon over the sausage-pepper mixture evenly. Top with remaining bread. Gently press so peaks still show—this ensures crispy crowns later.

Whisk the custard

In a large bowl whisk eggs, then blend in maple syrup, Dijon, salt, nutmeg, and pepper. Stream in half-and-half until combined. Stir in 1 cup of the shredded cheese blend (reserve the rest for topping).

Soak & wrap

Pour custard evenly over casserole. Sprinkle remaining cheese. Cover tightly with plastic wrap, then foil. Refrigerate at least 8 hours and up to 24 hours. Place the dish on a rimmed tray to catch potential sloshes.

Bake low & slow

In the morning, remove wraps, let stand at room temp while oven preheats to 325 °F. Bake on center rack 55–65 minutes until puffed and internal temp hits 170 °F. If browning too quickly, tent loosely with foil the last 15 min.

Rest & serve

Let casserole rest 10 minutes—this sets the custard for neat squares. Garnish with chopped chives, drizzle with warm maple syrup, and serve alongside fresh fruit or a citrus salad.

Expert Tips

Cold-oven start

No need to preheat: putting the cold dish into a gently warming oven prevents the glass from thermal shock and gives the center a head start.

Prevent sogginess

Pat roasted peppers and spinach dry before mixing; extra moisture dilutes the custard and can cause a watery layer.

Overnight timing

A 16-hour soak is the sweet spot for flavor and structure; beyond 24 hours the bread can break down too much.

Extra puff

For a soufflé-like rise, separate the eggs: beat whites to soft peaks and fold into the custard just before pouring.

Cheese crust hack

Reserve cheese for the final 10 min of baking; sprinkling too early can cause a rubbery film instead of a lacy crust.

Sleep-in option

Bake the casserole the night before, chill, then reheat squares at 300 °F for 15 min—convenient for staggered brunch schedules.

Variations to Try

Coastal Crabcake: Swap sausage for 8 oz lump crab + ½ cup minced scallions; season custard with Old Bay and lemon zest.
Green Chile & Chorizo: Use Mexican chorizo, poblanos, and Monterey Jack. Serve with salsa verde.
Mushroom & Herb (vegetarian): Replace sausage with 12 oz sautéed creminis and 2 Tbsp white miso for umami.
Everything-Bagel: Add 1 tsp everything seasoning to custard and top with thinly sliced smoked salmon after baking.

Storage Tips

Refrigerate: Cool leftovers within 2 hours, cut into squares, and store in an airtight container up to 4 days.

Freeze: Wrap individual squares in plastic, then foil; freeze up to 2 months. Thaw overnight in fridge and reheat at 300 °F for 20 min or microwave 60–90 seconds.

Make-ahead mini casseroles: Assemble in 12 greased muffin cups; reduce bake time to 25 min. Freeze on tray, then transfer to bag for quick single-serve breakfasts.