Breakfast + Brunch Eat

Loaded Veggie Make-Ahead Breakfast Casserole

Perfect to feed a family on Christmas morning!

This savory make-ahead breakfast casserole is loaded with cheese and vegetables—perfect to feed a family on Christmas morning or at a festive brunch. Plus, the leftovers save really well!

Loaded Veggie Make-Ahead Breakfast Casserole

Course Breakfast
Cuisine American
Keyword breakfast casserole, eggs
Prep Time 30 minutes
Cook Time 40 minutes


  • 2 tablespoons Extra virgin olive oil
  • 1 medium yellow onion, diced
  • 1 orange bell pepper, diced
  • 1 red bell pepper, diced
  • 10 ounces sliced shiitakes
  • 1 teaspoon Kosher salt, divided
  • 10 ounces frozen chopped broccoli, defrosted
  • 10 eggs
  • 3 cups whole milk
  • 1 teaspoon dry mustard
  • Freshly ground black pepper, to taste
  • 4 cups day-old white or Italian bread cubed (about 8-10 slices)
  • 1 cup shredded gruyere, divided (I shred my own)
  • 1 cup shredded cheddar cheese, divided (I shred my own)
  • 4 tablespoons grated parmesan or pecorino, divided


  1. 1. Heat the oil in a large skillet over medium-high heat. Add the onion, peppers, and shiitakes, along with ½ teaspoon of the salt. Cook, stirring from time to time, for 5-7 minutes, until the vegetables have softened, browned a bit, and decreased in volume. Remove from heat.

  2. 2. While the other vegetables cook, place the defrosted broccoli on a thick layer of paper towels and cover with another thick layer. When the veggies in the skillet have cooked as noted above, press down gently on the paper towels to remove moisture from the broccoli. The add broccoli to the skillet and stir to incorporate.
  3. 3. Crack the eggs into a large mixing bowl and beat well with a fork. Stir in milk, dry mustard, the rest of the salt, and a few grinds of black pepper. Add bread cubes and stir to moisten. Then stir in all the vegetables, the parmesan or pecorino, and three-quarters of the gruyere and cheddar. Pour the whole mixture into a 9 x 12 baking dish and sprinkle with the remaining cheese. Cover and refrigerate overnight or for at least a few hours before proceeding. Remove from fridge about an hour before baking if possible.

  4. 4. An hour before serving time, preheat oven to 375 degrees F with a rack in the center. Bake uncovered for about 40 minutes, until puffed and golden. Serve hot.

In my kitchen, best served with a mimosa! 😉

Bon Appétit!

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