Bacon and Gruyere Strata

In a large bowl, whisk together eggs, milk, 1 tsp kosher salt (2 tsp for 8 servings), and plenty of freshly ground black pepper. Once bacon is crispy, transfer to a paper-towel-lined plate. Pour off and discard any fat from baking sheet, then spread ciabatta onto sheet. Bake on top rack until golden-brown and mostly dry, 7-9 minutes (9-10 minutes for 8 servings).

Meanwhile, melt 2 TBSP butter (4 TBSP for 8 servings) in a large pan over medium-high heat. Add onion; season with salt and pepper. Cook, stirring until softened, 4-5 minutes. Meanwhile, roughly chop bacon.

Reduce oven to 375 degrees. Add bacon, ciabatta, onion, asparagus, chopped basil, and half the gruyere to bowl with egg mixture. Stir to thoroughly combine. Let soak until bread has absorbed some liquid, about 5 minutes. Pour into prepared baking dish. Sprinkle with mozzarella and remaining gruyere.

Spray a large piece of aluminum foil with nonstick cooking spray. Cover baking dish, spray side-down, with prepared foil. Bake strata on top rack, covered, for 20 minutes (30 minutes for 8 servings). Remove foil and continue baking until lightly browned, puffed up, and cooked through, 25-35 more minutes. (To check if strata is cooked through, poke a paring knife into center of dish. Center should be moist but not runny.) Remove from oven and let rest at least 5 minutes before serving.