Easy Egg Bake Casserole Recipe

There is a moment, about ten minutes before this comes out of the oven, when the whole kitchen smells like a little countryside bakery — toasted bread, warm cheese, sweet roasted tomatoes. This egg bake casserole is how I feed a table full of people on a slow morning without standing over a skillet flipping eggs two at a time. You whisk, you layer, you bake, and then you sit down with your coffee like everybody else.

It is built like a savory strata: big, crusty cubes of bread soak up a well-seasoned egg custard, fresh spinach wilts right into the mix, and halved cherry tomatoes bake up juicy and bright on top. The bread tips that peek out of the custard turn deep golden and crisp — exactly the craggy, bronzed tops you see in the photo — while everything underneath stays soft, fluffy and custardy. It works for Easter brunch, Christmas morning, or a regular Saturday, and it can be assembled the night before.

Why This Casserole Makes Breakfast the Easy Part

• No skillet juggling — everything bakes in one dish at the same time, so nobody eats in shifts and nobody gets cold eggs.
• Those crispy bread tops — the cubes that stick up out of the custard toast into crunchy, golden crouton-like peaks, the best bite in the dish.
• Veggies baked right in — spinach and cherry tomatoes are part of the casserole, not an afterthought on the side.
• Make-ahead by design — assemble it tonight, refrigerate, and bake it in the morning. The soak actually improves it.
• Feeds eight generously — one 9×13 dish, a pot of coffee, and breakfast is handled.

The Ingredients (Bakery Bread, Garden Veggies, One Good Custard)

For the bake:

• 8 cups crusty bread cubes (about 12 oz / 340 g), cut into big 1½-inch chunks — French bread, Italian loaf, or sourdough. Big cubes are what give you those tall, toasty peaks in the photo. Day-old bread is perfect; fresh works if you dry it (see the tips).
• 1 tablespoon olive oil — for wilting the spinach.
• 1 small yellow onion, finely diced — it melts into the bake and adds a quiet sweetness. You will not see it in the finished dish, but you would miss it.
• 2 cloves garlic, minced — just enough to make the spinach taste like something.
• 5 oz (140 g) fresh baby spinach, roughly 5 packed cups — it looks like a mountain and wilts down to almost nothing, which is why we start with so much.
• 2 cups (about 10 oz / 300 g) cherry tomatoes, halved — half get folded through the bake; half go on top, cut side up, so they roast into the bright red jewels you see in the photo.
• 2 cups (about 8 oz / 225 g) shredded mozzarella cheese, divided — the pale, melty cheese that stretches through the whole casserole. Low-moisture mozzarella melts cleanest.
• 1/4 cup (25 g) grated Parmesan cheese — scattered over the top for salty, golden spots.

For the custard:

• 10 large eggs — the backbone of the bake. Room temperature eggs whisk smoother, but cold ones work too.
• 1 1/2 cups (360 ml) whole milk — half-and-half makes it richer; whole milk keeps it fluffy and light.
• 1 teaspoon Dijon mustard — you cannot taste it as mustard; it just makes the eggs taste more like themselves.
• 1 teaspoon Italian seasoning — those little herb flecks through the custard in the photo.
• 1 teaspoon fine salt and 1/2 teaspoon black pepper — eggs need confident seasoning; under-salted is the number one reason egg bakes taste bland.
• Butter or cooking spray, for the dish.

How to Make It: Wilt, Whisk, Layer, Bake

1. Heat the oven and prep the dish. Set the oven to 350°F (175°C). Butter a 9×13-inch baking dish (the glass dish in the photo is ideal — you can watch the sides turn golden) and set it aside.
2. Wilt the spinach. Heat the olive oil in a large skillet over medium heat. Add the onion and cook for 3 to 4 minutes until soft. Stir in the garlic for 30 seconds, then add the spinach in big handfuls, tossing until it just wilts, 2 to 3 minutes. Tip everything into a colander or onto a clean towel and squeeze out as much liquid as you can — this step decides whether your bake is fluffy or soggy.
3. Whisk the custard. In a large bowl, whisk the eggs until the yolks and whites are completely blended. Whisk in the milk, Dijon, Italian seasoning, salt, and pepper until smooth.
4. Build the base. Scatter the bread cubes in the dish in an even layer. Spread the squeezed spinach mixture over the bread, fold half of the cherry tomato halves through, and sprinkle over 1 1/2 cups of the mozzarella.
5. Pour and press. Pour the custard slowly and evenly over everything. Press the bread down gently with the back of a spoon so every cube gets a drink of custard — a few proud peaks sticking up are good; they are the ones that will toast. Rest 15 minutes on the counter (or cover and refrigerate overnight; see the tips).
6. Top it like the photo. Arrange the remaining tomato halves over the surface, cut side up. Scatter the last 1/2 cup of mozzarella and all of the Parmesan over the top.
7. Bake covered, then uncovered. Cover loosely with foil and bake for 20 minutes. Remove the foil and bake 25 to 30 minutes more, until the casserole is puffed, the center is set (a knife slipped into the middle comes out clean), and the bread peaks are deep golden brown like the photo. The center should jiggle only very slightly.
8. Rest, then serve. Rest 10 minutes — the custard finishes setting and the slices come out clean. Cut into 8 generous squares and serve warm, straight from the dish.

Sofia’s Expert Tips (Fluffy Center, Crispy Tops)

• Squeeze the spinach like you mean it. Spinach gives off a shocking amount of water. Press it in a towel until it feels almost dry. Watery spinach is the number one cause of a soggy, sunken egg bake.
• Dry bread drinks better. Fresh, soft bread turns to mush in custard. If your loaf is fresh, spread the cubes on a sheet pan and dry them in a 300°F (150°C) oven for 8 to 10 minutes first. Day-old bread needs nothing.
• Season the custard, not the top. Salt added after baking only sits on the surface. The teaspoon of salt goes into the custard so every bite is seasoned — taste the raw custard once and you will never under-season again. (Yes, chefs do this.)
• The overnight soak is a gift, not a shortcut. Resting the assembled casserole in the fridge for 8 to 12 hours lets the bread absorb the custard fully, and it bakes up even puffier. Just let it sit on the counter for 20 to 30 minutes while the oven heats, and add 5 minutes to the bake if it goes in cold.
• Do not skip the covered start. The foil in the first 20 minutes traps steam so the center sets gently instead of the top racing to brown while the middle is still liquid.
• Pull it at the jiggle. Eggs keep cooking from the dish’s heat after they leave the oven. If the center looks completely firm in the oven, it will be rubbery on the plate. Slight jiggle in the very middle, clean knife — that is your moment.

Easy Variations Worth Trying

• Farmers market swap: trade the spinach for chopped kale (wilt it 2 minutes longer) and the cherry tomatoes for diced bell peppers. Same method, heartier greens.
• Cheese lover’s version: swap half the mozzarella for shredded Gruyère or sharp white cheddar. You will get the same melty pull with a deeper, nuttier flavor.
• Everything bagel style: skip the Italian seasoning and finish the top with 2 teaspoons of everything bagel seasoning before baking. Wonderful with the tomatoes.
• Small-batch dish: halve everything and bake in an 8×8-inch dish for 35 to 40 minutes total. Same crispy tops, sized for two or three people.

How to Store, Freeze and Reheat It

• Fridge: cool leftovers, cover the dish (or move squares to a container), and refrigerate for up to 3 days.
• Reheat like fresh: warm squares in a 350°F (175°C) oven for 10 to 12 minutes — the tops crisp back up beautifully. The microwave works in a pinch (about 90 seconds), but the bread goes soft.
• Freezer: bake first, cool completely, then wrap individual squares and freeze for up to 2 months. Thaw overnight in the fridge and reheat in the oven as above.
• Assembled and unbaked keeps 12 hours in the fridge, covered — that is the make-ahead window. Longer than that and the bread starts to break down.

FAQs

Save this recipe for the next morning you want brunch to feel special without any morning work — assemble it tonight, and tomorrow the oven does everything while you pour the coffee.

More recipes you’ll love: French Toast Casserole, Hash Brown Casserole and Cheesy Hashbrown Casserole.