Family Suppers Breakfast Pans

Milk-and-Egg Veggie Breakfast Casserole

A full breakfast casserole built on eggs, milk, potatoes, and vegetables, with enough structure to feed a table and reheat well the next morning.

  • By Ruthann
  • Published March 17, 2026
  • Last reviewed March 17, 2026
  • Total time 75 min
  • Yield 10 servings

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This casserole is for the kind of morning when one pan needs to steady the house before the day starts pulling in ten directions. Eggs, milk, potatoes, and vegetables make a better breakfast than another round of scattered snacks, especially when the leftovers still reheat kindly.

It also respects perishables. A good milk-and-egg recipe should help families use what needs using before it turns into waste.

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Recipe details

Timing & yield

Prep
25 minutes
Cook / bake
50 minutes
Total
75 minutes
Yield
10 servings

Ingredients

Vegetable base

  • 2 tablespoons butter
  • 1 medium onion, diced
  • 1 red bell pepper, diced
  • 8 ounces mushrooms, diced
  • 1 teaspoon kosher salt, divided
  • 1/2 teaspoon black pepper, divided
  • 4 cups frozen hash browns, thawed

Custard

  • 10 large eggs
  • 3 cups milk
  • 1 teaspoon dry mustard
  • 1 cup shredded cheddar cheese

Method

  1. Step 1. Heat the oven to 350 degrees Fahrenheit and grease a 9x13 baking dish.
  2. Step 2. Melt the butter in a large skillet over medium heat, then cook the onion, bell pepper, and mushrooms with 1/2 teaspoon of the salt and 1/4 teaspoon of the pepper until the vegetables soften and most of the mushroom moisture cooks away.
  3. Step 3. Spread the hash browns in the baking dish, then scatter the cooked vegetables evenly over the top so every section gets some of each one.
  4. Step 4. In a large bowl, whisk the eggs, milk, dry mustard, remaining salt, and remaining pepper until the yolks and whites are fully broken up and the custard looks even.
  5. Step 5. Stir in the cheddar, then pour the custard over the vegetables and potatoes, pressing lightly so the potatoes are moistened from edge to center.
  6. Step 6. Bake for 40 to 45 minutes, until the center reaches 160 degrees Fahrenheit and no longer ripples when the dish is nudged.
  7. Step 7. Rest the casserole for 10 minutes before serving so the custard finishes setting and the slices hold together.

Equipment

  • large skillet
  • mixing bowl
  • 9x13 baking dish

Storage & safety

Refrigerate leftovers within 2 hours and use within 4 days. Reheat covered so the eggs stay tender and the potatoes do not dry around the edges.

Safe minimum internal temperature: 160°F

Rest time: 10 minutes

Because this is a dairy-rich egg casserole, refrigerate it promptly and do not leave it sitting out through a long brunch.

Reheat leftovers to 165°F before serving hot again.

Egg casseroles should be baked until the center is fully set, not loose.

Troubleshooting

The center stayed wet
Return the casserole to the oven in 5-minute increments until the middle is set and the thermometer reaches 160 degrees Fahrenheit.
The vegetables made the casserole watery
Let the pan rest longer, and next time cook the mushrooms until their liquid is mostly gone before they go into the dish.

Recipe rescue notes

The casserole tastes flat after baking

Likely cause: The vegetables were underseasoned before the custard went in.

Fix: Sprinkle a little more salt over the hot cut pieces and serve with salsa or chopped herbs to wake the pan up.

Next time: Season the vegetables in the skillet first, because the potatoes and eggs soften the seasoning once everything bakes together.

Substitutions

Mushrooms
Use thawed chopped spinach squeezed dry or extra bell pepper. — Keep watery vegetables as dry as you can before they go into the custard or the center may bake up loose.

Carryover / Next Meal Ideas

Breakfast burrito filling

Chop reheated leftovers and roll them into tortillas with salsa for a second breakfast that still feels like a real meal.

  • Warm the filling first so it rolls cleanly and does not tear the tortillas.

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