# What You Need:
→ Custard Mixture
01 - 3 large eggs
02 - 3/4 cup whole milk
03 - 1/4 cup heavy cream
04 - 1 tablespoon granulated sugar
05 - 1/2 teaspoon kosher salt
06 - 1/2 teaspoon ground black pepper
07 - 1/2 teaspoon Dijon mustard (optional)
→ Bread
08 - 8 slices brioche or challah bread, about 1/2 inch thick
→ Cheese Filling
09 - 8 slices Gruyère or sharp cheddar cheese, or a combination
→ For Cooking
10 - 2 tablespoons unsalted butter
11 - 1 tablespoon neutral oil (such as canola)
# Steps:
01 - Whisk together eggs, whole milk, heavy cream, sugar, kosher salt, black pepper, and Dijon mustard (if using) in a shallow bowl until combined.
02 - Place 4 slices of bread on a work surface, layer each with 2 slices of cheese, then top with remaining slices to form sandwiches.
03 - Warm a large nonstick skillet or griddle over medium heat, adding 1 tablespoon butter and 1/2 tablespoon oil; swirl to coat the surface.
04 - Immerse each sandwich in the custard mixture, coating both sides thoroughly without allowing bread to become soaked through.
05 - Arrange custard-coated sandwiches in the skillet; cook 3 to 4 minutes per side, pressing gently, until golden brown and cheese is fully melted. Cook in batches if necessary, replenishing butter and oil as needed.
06 - Transfer cooked sandwiches to a cutting board; allow to rest for 2 minutes before slicing and serving warm.