Mushroom and Swiss Chard Strata With Gruyere - Ellie Krieger

Ingredients

• 2 tablespoons extra-virgin olive oil, plus more for the baking dish
• 1 medium bunch Swiss chard (about 10 ounces)
• 1 pound mixed mushrooms, sliced, and coarsely chopped if large
• 1 medium onion, diced
• 2 cloves garlic, minced
• 10 large eggs
• 2 cups 1% low-fat milk
• 1 tablespoon Dijon mustard
• 1 cup packed, shredded Gruyère cheese (4 ounces)
• 2 teaspoons fresh thyme leaves or 3/4 teaspoon dried
• 1 teaspoon chopped fresh sage or 1/2 teaspoon dried
• 1/2 teaspoon kosher salt
• 1/2 teaspoon freshly ground black pepper
• 8 cups cubed crusty whole-grain bread (1-inch cubes)