# What You'll Need:
→ Breads
01 - 12 slices thick-cut sourdough bread, crusts on
→ Cheeses
02 - 1 1/2 cups shredded sharp cheddar cheese
03 - 1 cup shredded Gruyère cheese
04 - 1 cup shredded mozzarella cheese
05 - 1/2 cup cream cheese, softened
→ Dairy & Liquids
06 - 1 1/2 cups whole milk
07 - 3 large eggs
08 - 1 tablespoon Dijon mustard
09 - 4 tablespoons unsalted butter, melted
→ Vegetables & Add-Ins
10 - 2 large heirloom tomatoes, sliced
11 - 1 small red onion, thinly sliced
12 - 6 strips cooked bacon, chopped (optional; omit for vegetarian)
13 - 1/2 cup baby spinach leaves
14 - 1/4 cup chives or green onions, thinly sliced
→ Seasonings
15 - 1 teaspoon garlic powder
16 - 1 teaspoon smoked paprika
17 - 1/2 teaspoon salt
18 - 1/2 teaspoon black pepper
# Steps to Follow:
01 - Preheat oven to 375°F. Lightly grease a 9x13-inch casserole dish with butter or nonstick spray.
02 - In a large mixing bowl, whisk eggs, whole milk, Dijon mustard, garlic powder, smoked paprika, salt, and black pepper until fully combined.
03 - Arrange 6 slices of sourdough bread in the base of the casserole dish, trimming to fit as needed. Evenly spread half the softened cream cheese over the bread slices.
04 - Distribute half of the sharp cheddar, Gruyère, and mozzarella cheeses evenly over the bread. Add half of the sliced tomatoes, red onion, spinach leaves, and chopped bacon if using.
05 - Repeat with remaining bread slices, cream cheese, shredded cheeses, tomatoes, red onion, spinach, and bacon to create a second layer.
06 - Pour the egg and milk mixture evenly over the entire casserole. Gently press down on the layers to help the bread absorb the liquid.
07 - Drizzle melted unsalted butter over the top layer. Sprinkle with chives or green onions.
08 - Cover casserole with foil and bake for 25 minutes.
09 - Remove foil and bake an additional 10 minutes, until golden brown and bubbling.
10 - Allow casserole to rest for 5 to 10 minutes before slicing into squares. Serve warm.
