Kale and Appenzeller Strata | culture: the word on cheese

Ingredients

• 1 tablespoon extra-virgin olive oil
• 1 medium-large red onion (minced)
• 6 garlic cloves (minced)
• 3 cups chopped lacinato kale
• 1 teaspoon sea salt
• 1/2 teaspoon black pepper
• 1/2 teaspoon chili flakes
• 1 teaspoon butter
• 1 pound sourdough bread loaf cubed
• 2 cups finely grated Appenzeller
• 1 cup finely grated aged white cheddar
• 1/2 cup finely grated parmesan
• 10 large eggs
• 2.5 cups milk
• 3 tablespoons Dijon mustard