Step 1: Preheat Oven and Prepare Baking Dish

Begin by preheating your oven to 375°F (190°C). This ensures that the croissants bake evenly and achieve that perfect golden-brown color. While the oven is heating, lightly grease a 9x13-inch baking dish. This prevents the croissants from sticking and makes for easy cleanup later. You can use cooking spray, a drizzle of olive oil, or a pat of butter to grease the dish.

Step 2: Prepare Croissants

Carefully slice each croissant in half horizontally, creating a top and bottom piece. Be gentle to avoid tearing the delicate layers. Lay the bottom halves of the croissants on a clean work surface, ready to receive their delicious fillings.

Step 3: Layer the Cheese and Ham

On the bottom half of each croissant, place a half slice of cheddar cheese. This creates a delicious base layer. Follow with a generous slice of deli-cut ham, ensuring it covers the cheese. Top the ham with another half slice of cheddar cheese, effectively sandwiching the ham between layers of melted cheesy goodness. Using smoked cheddar adds an extra layer of flavor, but regular cheddar works just as well.

Step 4: Create the Honey-Mustard Spread

In a small bowl, combine the softened unsalted butter, yellow mustard, honey, and Worcestershire sauce. Mix these ingredients thoroughly until you achieve a smooth and creamy consistency. The softened butter will incorporate easily, creating a luscious spread. Taste and adjust the amount of Worcestershire sauce to your liking. This spread is the secret ingredient that elevates these croissants to gourmet status.

Step 5: Assemble and Spread

Spread the honey-mustard mixture evenly on the inside of the top half of each croissant. This ensures that every bite is bursting with flavor. Then, carefully place the top halves of the croissants over the ham and cheese fillings, creating a sandwich.

Step 6: Arrange in Baking Dish

Carefully arrange the assembled croissant sandwiches in the prepared baking dish. Ensure they are not too crowded to allow for even baking and browning.

Step 7: Apply Egg Wash and Sprinkle with Poppy Seeds

In a small bowl, whisk together the egg white with a splash of water (about a teaspoon). This creates a simple egg wash that will give the croissants a beautiful sheen and golden color. Brush the tops of the croissants evenly with the egg wash. Finally, sprinkle the tops generously with poppy seeds for added texture and visual appeal.

Step 8: Bake

Place the baking dish in the preheated oven and bake for 15-18 minutes, or until the cheese is melted, bubbly, and golden brown, and the croissants are heated through. Keep a close eye on them to prevent burning.

Step 9: Serve Warm

Once the croissants are golden brown and the cheese is melted and bubbly, remove them from the oven and let them cool slightly before serving. The melted cheese will be very hot! Serve warm and enjoy the irresistible combination of flavors and textures.