This zucchini breakfast casserole, starring cheese, bacon, sour cream, and, of course, fresh summer squash, is the kind of dish you eat once and then proceed to gush about forever. Everything you love about a summertime brunch spread — creamy eggs, chunks of zucchini, crunchy sourdough, crispy bacon — is piled into your cast iron skillet to create a veg-heavy meal you won't be able to get enough of.
Your New Favorite Way to Use Up Summer Zucchini
Come mid-summer when you're inundated with zucchini, you're likely in need of a new way to use it up — and that's exactly where this casserole comes into play. The thick slices of the bright-green squash do double duty in this dish by working an extra helping of veggies into your day while also balancing out the richness of the sour cream, bacon, and cheese.
While we typically recommend cooking summer squash before adding it into anything with an egg base (say, a frittata), you keep it raw in this recipe. The thick pieces hold their shape, softening just a bit without becoming mushy. The large pieces of toasty sourdough absorb the small amount of moisture released from the zucchini and act as a golden, crunchy topping.
A Fast and Easy Way to Dry Out Bread for Casseroles
Many stratas and egg casseroles will call for stale (or day-old) bread, which better absorbs the egg-y custard. But if you're working with a freshly baked loaf, you don't have to wait until tomorrow to get cooking. Instead, spread the bread cubes onto a rimmed baking sheet in an even layer. Toast, stirring halfway through, until the cubes feel dry and hard, but are still very pale, 15 to 20 minutes total. Remove from the oven and set aside to cool slightly.
Best Zucchini Breakfast Casserole
Serves 6 to 8
Prep time: 5 minutes to 10 minutes ; cooking time: 45 minutes to 50 minutes
bacon (about 8 slices)
day-old sourdough bread, cut into 1/2-inch cubes (about 3 cups)
1 1/2 pounds
zucchini (2 to 3 medium zucchini), cut into 1/2-inch-thick half-moons
freshly ground black pepper
finely grated Parmesan cheese (about 2 ounces), divided
Arrange a rack in the middle of the oven and heat to 375°F.
Place the bacon in a large cast iron skillet over medium-low heat. Cook, flipping halfway through, until the fat has rendered out and the bacon is crispy, about 10 minutes total. Remove the pan from the heat. Transfer the bacon to a paper towel-lined plate.
Drain all but 1 tablespoon of the rendered bacon fat from the skillet. Crumble the bacon into the skillet. Add the bread and zucchini, and toss to coat with the bacon fat.
Whisk the eggs in a large bowl until the whites and yolks are completely mixed and the eggs are a bit frothy. Add the sour cream, milk, mustard, salt, pepper, and half the cheese and whisk to combine. Pour the eggs into the skillet and top with the remaining cheese.
Bake until the eggs are set and casserole is light golden-brown, 35 to 40 minutes. Let cool for 5 minutes. Top with sliced scallions and serve warm.
Make ahead: The casserole can be assembled, covered, and stored in the refrigerator overnight. Let sit at room temperature for 20 minutes before baking.
Storage: Leftovers can be stored in a covered container in the refrigerator for up to 5 days.