Creamy cheddar broccoli casserole on BakeSpace.com

Ingredients

• 1 ½ ounces rustic sourdough bread, torn into 1/2-inch pieces (1 cup)
• 3 tablespoons canola oil, divided
• 10 cups chopped broccoli florets (from 3 medium heads)
• ¼ cup water
• 3 cups chopped fresh cremini mushrooms (about 8 oz.)
• ½ cup finely chopped yellow onion
• 2 teaspoons minced garlic
• 2 tablespoons all-purpose flour
• 2 cups whole milk
• ½ cup canola mayonnaise
• ½ teaspoon plus 1/8 tsp. kosher salt
• ½ teaspoon black pepper
• .13 teaspoon ground nutmeg
• Cooking spray
• 1 ½ ounces cheddar cheese, finely shredded (about 1/3 cup)